Maohong Fan

Improving catalytic performance of syngas conversion to form C 2 oxygenates on the Cu-based catalyst is still a challenge. Here, 2D h-BN material covered Cu confined catalysts (xh-BN/Cu) with different spatial dimensions are rationally designed to unravel the function of spatial dimension in tuning the activity and selectivity of C 2 oxygenates. The results show that the spatial dimension caused by h-BN coating in the h-BN/Cu catalyst can alter the dominant existence form of CH x (x=1-3) monomer and the corresponding activity and selectivity, in which the confinement effect arisen from h-BN coating with different spatial dimensions is confirmed to be the determined factor instead of the electronic effect. The screened 4.0h-BN/Cu catalyst has outstanding catalytic performance toward the production of dominant CH x (x=1-3) monomer and C 2 oxygenates. The finding provides the new design principle to rationally construct 2D material covered metal confined catalysts by adjusting the confined spatial dimension to improve catalytic performance.

The reaction mechanisms of CO oxidative coupling to dimethyl oxalate (DMO) on different β-Mo 2 C(001) based catalysts have been studied by the density functional theory (DFT) method. The activity and selectivity of DMO formation on Mo termination of β-Mo 2 C(001) are poor, and its C termination has no catalytic activity. After loading a Cu monolayer, the Cu ML /Mo 2 C(001)-Mo catalyst shows poor activity for the CO oxidative coupling reaction, but on Cu ML /Mo 2 C(001)-C, the CO oxidative coupling reaction can occur owing to the synergistic effect between the Cu monolayer and Mo 2 C(001), and it is expected to be a catalyst to replace precious metal Pd in DMO generation. Furthermore, the d-orbital state density of the Cu monolayer on Cu ML /Mo 2 C(001)-C is most similar to that of the Pd monolayer of Pd(111), which is the reason why Cu ML /Mo 2 C(001)-C has high activity and selectivity to DMO on the CO oxidative coupling reaction.

Phase change materials have been used in buildings as effective latent energy storage elements because of their remarkable capability of storing thermal energy and thus have attracted great attention to ameliorate severe environmental issues caused by greenhouse gas emissions. However, the drawbacks of phase change materials such as leakage during solideliquid phase transition process and poor thermal conductivity restrain their further development. This review paper summarizes the recent research progress in the design and synthesis of shape-stabilized phase change materials using biomass-derived porous carbons as solid supports. These carbon supports from waste resources exhibit unique features, including renewable, cost-effective, considerable thermal transfer ability, and diverse microstructures that are inherited from biomass. The applications of shape-stabilized phase change materials with composites developed from biomass in active and passive building systems are reviewed. This review concludes that employment of shape-stabilized phase change material in buildings would contribute to a reduced indoor air temperature fluctuation, improved thermal performance, and enhanced building energy efficiency. This review also provides valuable insights and promising perspectives for potential research and development of phase change materials from renewable feedstocks focused on applications in building and construction industry.

The objective is to find a new pathway for significant reduction in CO2 capture energy consumption. Specifically, nanoporous TiO(OH)2 was used to realize the objective, which was desired as a catalyst to significantly accelerate the decomposition of aqueous NaHCO3, essentially CO2 desorption - the key step of Na2CO3/NaHCO3 based CO2 capture technologies from overall CO2 energy consumption perspective. Effects of several important factors on TiO(OH)2-catalyzed NaHCO3 decomposition were investigated. The quantity of CO2 generated from 0.238 mol/L NaHCO3 at 65 °C with catalyst is ~800% of that generated without the presence of catalyst. When a 12 W vacuum pump was used for carrying the generated CO2 out of reactor, the total amount of CO2 released was improved by ~2,500% under the given experimental conditions. No significant decrease in the catalytic effect of TiO(OH)2 was observed after five cyclic CO2 activated tests. In addition, characterizations with in-situ Fourier transform inf...

Visible-light-driven photocatalytic CO 2 reduction over ketoenamine-based covalent organic frameworks: role of the host functional groups Catalytic processes using covalent organic frameworks (COFs) as photocatalysts are greatly infl uenced by the functional groups on the skeleton of the COFs. In this content, there are some signifi cant diff erences in the photocatalytic performance of CO 2 reduction, when diff erent functional groups are introduced into the same COF's framework. The understanding of the eff ects of these groups on the light-absorption intensity, band gap, and charge transfer is greatly meaningful for the design and construction of COF-based photocatalysts for effi cient CO 2 reduction.

Hydrogen has been widely considered a clean fuel of the future, with the highest mass based energy density of known fuels. Water gas shift (WGS) and steam reforming (SR) are the major reactions used for hydrogen production, and improved catalysts are essential to the future of the WGS and SR processes. Much progress in the different aspects of these fields has been made recently, which includes approaches to preparation and characterization, doping and promotion, as well as evaluation of catalysts, especially nanocatalysts. Significant improvements have been realized in increasing the stability of the catalysts, the overall conversion of raw materials, and the hydrogen production selectivity. This review aims to introduce these hydrogen production processes, to present developments in these areas, and discusses recent improvements that have made noteworthy impacts.

Polyacrylonitrile (PAN) based carbon nanofiber (CNF) papers have unique physicochemical properties including flexibility, good electrical conductivities, and excellent mechanical properties for supercapacitor electrodes. However, their surface-to-weight ratios and density of active sites on the surface are much poorer than those of other active carbons. Herein, a simple, renewable, multifunctional, and effective way is described to fabricate three-dimensional (3D) heteroatom-enriched porous PAN-based CNF papers by adding a moderate amount of microalgae-derived oil that has a large fraction of light compounds and nitrogen-and oxygen-containing functional components. CNF papers with enhanced porosity and large specific surface area, unique pore structure, and 3D heteroatom-enriched surfaces were successfully fabricated by stabilization and carbonization of PAN nanofibers with the algae oil. The as-fabricated algal-30% CNF paper is scalable and highly flexible as a freestanding supercapacitor electrode material and can deliver a specific capacitance of 272 F/g under a scan rate of 10 mV/s with noticeably high charge-discharge cycling stability, with 94% retained even after 10,000 cycles. The fabrication mechanism and the enhancement of the electrochemical behaviors of three-dimensional, heteroatom-enriched, porous CNF papers are proposed. Our work underlines the promise of algae oil-modified PANbased CNF papers for high-capacity supercapacitor electrode materials.

This paper contains a study of the oxidation of sulfur dioxide using microscale and nanoscale iron oxide as catalysts. A comparison of the catalytic performance of microscale and nanoscale iron oxides showed that nanoscale iron oxide generally is more effective than microscale iron oxide in regard to catalyzing the oxidation of sulfur dioxide. The reaction orders, with respect to the reactants sulfur dioxide and oxygen, were 1 and 0.24, and 1 and 0.30 when microscale and nanoscale iron oxides, respectively, were used as catalysts. Furthermore, the activation energy of catalytic oxidation of sulfur dioxide with microscale iron oxide is 88.9% higher than that with nanoscale iron oxide.

h i g h l i g h t s The effect of Rh crystal phase on the catalytic performance in syngas-toethanol is for the first time identified. The fcc Rh exposes much denser active facets compared to the hcp Rh. The fcc Rh exhibits higher intrinsic activity for CH and ethanol formation than the hcp Rh. Compared to Ni, Ru, Co and Cu, the fcc Rh realizes a balance between CH and undissociated CO/CHO. The fcc Rh is still superior to the hcp Rh for Fe-modified Rh-based catalysts.

Oxygen vacancies can regulate the energy band structure of semiconductor photocatalytic materials, and serve as electron traps and active sites to improve the photocatalytic activity of the photocatalyst. Herein, we prepared Bi 2 MoO 6 flower spheres with a double-layer structure by a simple solvothermal method, and achieved the controllable introduction of oxygen vacancies through subsequent air calcination at different temperatures. The double-layer structure of Bi 2 MoO 6 improved the light absorption because of multiple reflections. Compared with the pristine Bi 2 MoO 6 , the introduction of oxygen vacancies regulated the energy band structure of Bi 2 MoO 6 , improved the separation and transfer rate of electron-hole pairs, and produced more active species such as h + and 1 O 2. Among all samples prepared, BMO-350 had the best activity, which could degrade 90.6% of ciprofloxacin (10 mg/L) within 80 min under the irradiation of 6000 K visible LED light. While under ultraviolet, 3000 K, 4500 K, 6000 K visible, red Led light and xenon lamp irradiation, the CIP degradation efficiency reached 94.9%, 73.77%, 85.9%, 89%, 16.24%, and 94.7%, respectively, demonstrated that the appreciable photocatalytic activity under the low energy light source.

The CO/CO 2 conversion mechanism on the calcium ferrite (CFO) surface in chemical looping was explored by a computational study using the density functional theory approach. The CFO catalytic reaction pathway of 2CO + O 2 → 2CO 2 conversion has been elucidated. Our results show that the Fe center in CFO plays the key role as a catalyst in the CO/CO 2 conversion. Two energetically stable spin states of CFO, quintet and septet, serve as the effective catalysts. The presence of the triplet O 2 molecule caused the conversion of these two spin-state structures into each other along the catalytic reaction pathway. A double release of CO 2 was predicted following this reaction mechanism. The rate-determining step is the formation of the 2CO 2 −CFO complex (P4) in the quintet state (19.0 kcal/mol). The predicted energy barriers for all the steps suggest that the proposed pathway is plausible.

In response to the worldwide over-standard carbon dioxide emission problem, this work synthesized a series of titanium dioxide/reduced graphene oxide composite aerogels (TiO 2-rGO) for photoconversion of CO 2 by a one-step hydrothermal and freeze-drying method. The prepared composite aerogel presents a high specific surface area of 287.3 m 2 /g and pore volume of 0.72 cm 3 /g, contributing to remarkable absorption capability of reactants and fast intraparticle molecular transfer. In the three-dimensional structure of rGO aerogel, TiO 2 with nano-rod shape (10-20 nm × 100-150 nm) is uniformly interspersed. Through applying the composite catalytic aerogel for the photocatalysis reaction, CO 2 was efficiently converted to MeOH, CH 4 , and EtOH, etc. The total yield of carbon generated by G-25Ti (TiO 2-rGO with 25 mmol Ti 4+) was found 15.7 times higher than that of the pure P25. The corresponding characteristic analysis demonstrated that the photocatalytic performance of TiO 2-rGO composite aerogel has been highly improved, originated from two folds: (1) the introduction of 3-D rGO to nano-rod shape TiO 2 promoted its light absorption efficiency, and more significantly (2) the specific chemical bonding sites and strong O˭C-O-Ti group between rGO and TiO 2 effectively mitigate the recombination of photogenerated electron-hole pairs. In this work, rod-like TiO 2-rGO composite aerogels prepared by using TiCl 4 as precursor for the first time have been found a new application in CO 2 reduction using visible sunlight.

In response to the worldwide over-standard carbon dioxide emission problem, this work synthesized a series of titanium dioxide/reduced graphene oxide composite aerogels (TiO 2-rGO) for photoconversion of CO 2 by a one-step hydrothermal and freeze-drying method. The prepared composite aerogel presents a high specific surface area of 287.3 m 2 /g and pore volume of 0.72 cm 3 /g, contributing to remarkable absorption capability of reactants and fast intraparticle molecular transfer. In the three-dimensional structure of rGO aerogel, TiO 2 with nano-rod shape (10-20 nm × 100-150 nm) is uniformly interspersed. Through applying the composite catalytic aerogel for the photocatalysis reaction, CO 2 was efficiently converted to MeOH, CH 4 , and EtOH, etc. The total yield of carbon generated by G-25Ti (TiO 2-rGO with 25 mmol Ti 4+) was found 15.7 times higher than that of the pure P25. The corresponding characteristic analysis demonstrated that the photocatalytic performance of TiO 2-rGO composite aerogel has been highly improved, originated from two folds: (1) the introduction of 3-D rGO to nano-rod shape TiO 2 promoted its light absorption efficiency, and more significantly (2) the specific chemical bonding sites and strong O˭C-O-Ti group between rGO and TiO 2 effectively mitigate the recombination of photogenerated electron-hole pairs. In this work, rod-like TiO 2-rGO composite aerogels prepared by using TiCl 4 as precursor for the first time have been found a new application in CO 2 reduction using visible sunlight.

The effect of addition of Ag to the catalytic properties of hollandite manganese oxide (HMO) was investigated for the oxidative acetalization of ethanol to diethoxyethane. Based on analysis with HRTEM, XRD, and EXAFS, Ag introduced onto HMO by deposition/precipitation was found to be present in different forms in the final catalyst depending on the calcination temperature. It could exist as nanoparticles on the outside surface of HMO nanorods for samples calcined at 60°C, and as Ag atoms intercalated into the tunnels of the HMO structure for samples calcined at 500°C. NH 3 desorption results showed that intercalation of Ag resulted in stronger Lewis acidic sites on HMO, which DFT computational results suggested to be due to Ag-induced electron redistribution in the HMO framework. The intercalation of Ag atoms also made the HMO more easily reducible by lowering the H 2 reduction temperature from 500 to 200°C. Consequently, the sample with intercalated Ag was more active for ethanol oxidation to acetaldehyde, achieving nearly 100% conversion of ethanol and acetaldehyde by 360°C, and acetalization of acetaldehyde with ethanol to produce diethoxyethane selectively, resulting in 93.5% diethoxyethane yield, which was 10% higher than with samples containing Ag nanoparticles on HMO. This study demonstrated a little-studied phenomenon in which a metal alters the catalytic properties of an oxide electronically but not structurally and without direct participation in the reaction.

Direct conversion of greenhouse gas carbon dioxide (CO 2) into lower olefins (ethylene, propylene and butene) provides an appealing approach to tackle CO 2 emission challenges. Admixed catalysts composed of metal/metal oxides and SAPO-34 have been widely used for catalytic CO 2 hydrogenation to lower olefins. However, interactions between metal/metal oxides and SAPO-34 remain obscure. Here, a novel family of admixed catalysts composed of Fe-Cu-K and SAPO-34 (Fe-Cu-K/SAPO) is developed for efficient catalytic CO 2 hydrogenation to lower olefins, which can achieve 49.7% CO 2 conversion and 62.9% selectivity of lower olefins, with CO selectivity <10%, over the optimal Fe 0.45 Cu 0.45 K 0.10 /SAPO-34 (with 1/1 mass ratio) catalyst. This exceptional performance is attributed to the change of structures, reducible properties and mass transfer resulting from strong interactions between metal/metal oxides and zeolites. First, SAPO-34 promotes the exposure of the active Cu-Fe (100) plane via disrupting the oriented growth process of Fe-Cu-K. Second, SAPO-34 boosts the reducible properties of Fe-Cu-K/ SAPO-34, promoting CO 2 adsorption and dissociation and thus resulting in the formation of q-Fe 3 C active sites for hydrocarbon formation. Finally, the main mass transfer method of long-chain hydrocarbons/methanol from Fe-Cu-K to SAPO-34 is gas diffusion, and the dispersion of Fe-Cu-K over SAPO-34 accelerates such gas diffusion. This study provides a potential novel pathway to solve the challenge of efficiently converting CO 2 into lower olefins and clarifies the effect of strong interactions between metal/metal oxides and zeolites on activities.

A macroscopic monolithic ZnSnO 3 /reduced graphene oxide aerogel (ZGA) composite was prepared and showed excellent adsorption and visible-light photocatalytic degradation activity for ciprofloxacin (CIP) wastewater. Especially, when the mass ratio of ZnSn(OH) 6 to graphene oxide (GO) is 1:2 (ZGA-4), the removal efficiency of CIP is almost reach 100%. The enhanced photoactivity of ZGA can be attributed to the optimized interfacial and electronic band structure reducing the recombination of photogenerated e −-h + pairs to produce more ⋅O 2 − and ⋅OH active species, which were confirmed by series of characterization techniques combine with density functional theory (DFT) calculations. Moreover, ZGA also exhibits satisfactory photostability, 98% CIP and the biological toxicity of CIP to Escherichia coli DH5a have been basically eliminated after four-cycle photocatalytic degradation.

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To maximize the utilization of Wyoming sub-bituminous coal and relieve the negative environmental impacts, green synthesis of supercapacitor materials from Powder River Basin (PRB) coal residual were employed to convert coal residuals to high-value carbon materials. The free-standing and binder-free activated carbon nanofibers (ACNFs) were synthesized eco-friendly in CO 2 through the carbonization and activation of polyaromatic hydrocarbon-rich extract, which was extracted from the supercritical PRB coal residual by THF Soxhlet. The flexible ACNFs featured various interconnected porous structures endowing the carbon nanofibers (CNFs) with a high specific surface area (743 m 2 g −1) and high total pore volume (0.613 cm 3 g −1). Moreover, the hightemperature activation in CO 2 enhanced the electrical conductivity and reduced the number of oxygen-containing compounds on the surface, which leads to lower charge-transfer resistance. The supercapacitor electrodes prepared from ACNFs have a specific capacitance of 409 F g −1 with some excellent and stable electrochemical performances. Therefore, the green synthesis of supercapacitor electrodes with the extract from PRB coal residuals can expand our horizons for the utilization of low-rank coal.

Single atom alloys (SAAs) catalysts become potential to provide excellent activity, selectivity, and stability toward the selective dehydrogenation of light alkanes by activating the desired C-H bond, however, the ideal metallic combination to best catalyze C 2 H 6 dehydrogenation is unclear yet. In this study, the activity and selectivity of ethane dehydrogenation on fifteen types of SAA catalysts (Co, Ir, Ni, Pd and Pt doped-Cu, Ag and Au) were fully investigated using DFT calculations and microkinetic modeling, and compared with that on the widely reported Pd, Pt, Cr and Pt 3 Sn. The results show that the activity of C 2 H 6 dehydrogenation to gas phase C 2 H 4 on all considered SAA catalysts has a relationship with C 2 H 4 desorption energy, the easier the desorption of C 2 H 4 is, the lower the activity of C 2 H 6 dehydrogenation to gas phase C 2 H 4 is. Similarly, C 2 H 4 selectivity has a relationship with C 2 H 5 adsorption energy, the weaker C 2 H 5 adsorption energy is, the higher C 2 H 4 selectivity is. Essential reason was explained based on the analysis of electronic properties. Thus, the dual descriptors, C 2 H 4 desorption energy and C 2 H 5 adsorption energy, were proposed to evaluate the activity and selectivity of C 2 H 6 dehydrogenation to gas phase C 2 H 4 , respectively. Among these SAA catalysts, the low cost NiCu catalyst with the best activity and selectivity toward gas phase C 2 H 4 formation is screen out, which is superior to the noble metals Pd and Pt widely reported. This study is expected to provide a simple and valuable method to screen out high performance SAA catalysts in alkane dehydrogenation to alkene.

Produced water is a major waste problem in oil production yet it also represents a potential water source if treated properly, especially in arid regions. In this study, we investigate the anaerobic treatability of an oilproduced water with extremely high chemical oxygen demand (COD) and total dissolved organic carbon (TOC) from Wyoming's Greater Green River Basin using anaerobic microcosms inoculated with a microbial consortium derived from a brewery wastewater treatment facility. The results demonstrate that for this water and an appropriate microbial inoculation, high-COD/TOC can be effectively removed with concomitant energy recovery as a form of methane. 93% and 89% of the COD and TOC were removed with a final high methane yield of 33.9 mmol/g carbon (848 μmol/g carbon/day). Chemical analyses showed that the ethylacetate-extractable compounds were much more amenable to biodegradation than the CH 2 Cl 2 extractable compounds. Furthermore, compounds that were added during drilling and completion remained in the water and contributed significantly to the COD and anaerobic degradability. This study demonstrates that produced waters are amenable to anaerobic biological treatment and also that thorough chemical analyses are necessary to fully understand the potential for treatment.

Biochar gasification is an essential stage of chemical looping biomass gasification, a promising sustainable source of energy that may limit anthropogenic carbon dioxide emissions. Here, the performance of calcium ferrite oxygen carriers (CaFe 2 O 4 , and Ca 2 Fe 2 O 5) on the CO 2 gasification reactivity and kinetics of pine wood char is investigated by a thermogravimetric analyzer. The morphology and graphitization degree of the pine wood derived biochar were characterized by using high-resolution transmission electron microscope (HRTEM) and Raman spectroscopy. A random pore model is established and the best matching structural parameter, J, is used to indicate the pore structure of the initial char samples. Results indicate that the activation energy under biochar with no oxygen carrier, biochar loaded with 10 wt% Fe 2 O 3 , 10 wt% Ca 2 Fe 2 O 5 , and 10 wt% CaFe 2 O 4 are 169.76 kJ/mol, 176.03 kJ/mol, 173.81 kJ/mol, and 178.83 kJ/mol, respectively. The introduction of oxygen carriers increases the activation energy for CO 2 gasification, potentially due to competition with calcium ferrite reduction, resulting in decreased CO 2 partial pressure.

The methylation reaction of methanol and toluene to xylenes has been carried out in Brønsted Acid Sites (BAS)− HZSM− 5, AlOH 2+ /BAS− HZSM− 5 and ZnOH + /BAS− HZSM− 5 catalysts. The stronger acid strengths are produced in AlOH 2+ /BAS− HZSM− 5 and ZnOH + /BAS− HZSM− 5 due to the synergistic effect of Lewis Acid Sites (LAS) and BAS compared to BAS− HZSM− 5, which is beneficial to the dissociation of methanol. AlOH 2+ / BAS− HZSM− 5 shows the highest activity for methanol dissociation with the strongest acid strength. The Gibbs free energy barrier is only 68.2 kJ⋅mol − 1 , but the formation of Para-xylene (PX) needs to overcome a high barrier of 129.2 kJ⋅mol − 1. However, ZnOH + /BAS− HZSM− 5 exhibits relative high activity for the formation of methoxy with the Gibbs free energy barrier of 113.9 kJ⋅mol − 1 , and 92.9 kJ⋅mol − 1 for PX. Meanwhile, the formation of PX is easiest among three xylenes. Therefore, ZnOH + /BAS− HZSM− 5 can be as the promising catalyst for the preparation of PX during methylation of toluene with methanol.

The development of cost-competitive and environmentally friendly CNFs is imperative. Wang et al. report the application of solar energy for generation of bioliquid from pinewood. Carbon nanofibers derived from these bioliquids are used for the fabrication of flexible binder-free electrodes with notable electrochemical properties.

Boron carbide B x C (x ¼ 1=6 À 10) powders were synthesized through a microwave-assisted carbothermic reduction reaction as a potential clean energy material. Their crystallographic structures and optical properties were characterized. X-ray diffraction and electron diffraction indicated that the synthesized B x C powders were amorphous. Electron energy-loss spectroscopy demonstrated that the composition of boron and carbon was in amorphous materials, and their chemical bonding were disclosed from Raman scattering spectroscopy. UVevis absorption spectroscopy indicated that the bandgap of the bulks varied from 2.30eV to 3.90eV, tuned by the boron/carbon element ratio. The synthesized powders were potential photovoltaic materials. A short-range ordering model was established to explain the optical properties.

h i g h l i g h t s Use of S-a typical catalyst poison enhancing catalytic performance of C 2 H 2 selective hydrogenation. Sulfur-containing Cu 2 O is superior to sulfur-free Cu 2 O in C 2 H 2 selective hydrogenation. Sulfur-containing Cu 2 O promotes C 2 H 4 formation and inhibits green oil precursor formation. S atom modifies Cu 2 O surface morphology and tunes the spatial scale of active region for associated reactions. S blocks the larger active region required for C 2 H 2 polymerization and C 2 H 4 hydrogenation.

A metal-assisted microwave treatment that converting raw coal powders into nano-graphite is presented. Specifically, four major factors are identified for successful conversion: (1) high temperature; (2) reducing environment; (3) catalyst; and (4) microwave radiation. Specifically, it is determined that the combination of the carbon sources (raw coal powders), the high temperature (microwave induced electric sparking), the reducing environment (the Ar/H 2 mixture), the catalyst (Cu foil), with the microwave radiations can generate nano-graphites. This novel approach utilizes the sparking induced by the microwave radiation on the fork-shape metal foils to generate high temperature (> 1000 o C) within few seconds. The small thermal load makes this method cost effective and has potential for higher temperature using metals with higher melting temperature. Refinement of this technique is possible to yield a higher quality and quantity of nano-graphite materials for a wider range of applications.

The conversion of CO 2 into valuable chemicals utilizing solar energy is one of the most promising approaches to solve the problems associated with global warming and energy shortage. Considering more and more covalent organic frameworks (COFs) that have been reported, the great potential of COFs as photocatalysts for CO 2 reduction is still appreciated to a limited extent. In the current work, Ru nanoparticles (NPs) loaded ketoaminebased COF (TpPa-1) catalysts, named Ru/TpPa-1, were developed for the photocatalytic reduction of CO 2 upon visible-light irradiation for the first time. Compared with TpPa-1, Ru/TpPa-1 catalysts exhibit a significantly enhanced activity for the photoreduction of CO 2. In combination with the results from some extensive characterizations, it is found that the interactions between the Ru NPs and TpPa-1 can enhance the visible-light harvesting and create a new way to extend the service life of photo-generated charge carriers via facilitating the electron transfer through the loaded Ru NPs. The current investigation, therefore, provides a photocatalytic approach for CO 2 fixation, enriches the theory of photocatalysis, and enlarges the application of COF-based materials.

h i g h l i g h t s Pd coordination affects the catalytic performance of single-atom Pd catalysts toward C 2 H 4 formation. PdM(1 0 0) (M = Cu, Ag, Au) with surface Pd coordination number of 8 exhibits the best catalytic performance. The d-band center of the single-atom Pd and its coordinated metal M affects the activity of C 2 H 4 formation. Surface Pd coordination number of 8 with the best performance is attributed to the moderate surface dband center. The valuable clues for the design of other partner metals alloyed singleatom Pd catalysts are provided.

The surface structure of the catalyst is a key factor to affect its catalytic performance toward the targeted reaction. In this work, aiming at revealing the surface structure influences of Pd-based alloy catalysts on the catalytic performance of C 2 H 2 selective hydrogenation, four kinds of surface structures of Pd-based alloy catalysts, including the core−shell Pd nL @M (M = Cu and Ag), the core−shell Pd nL @Pd x M y , the uniform alloy Pd 1 Cu 3 and Pd 1 Ag 1 , and the subsurface structure Pd 1L-M sub are engineered, and the corresponding catalytic performance is fully examined using DFT calculations. Our results reveal that the catalytic performance of C 2 H 2 selective hydrogenation is closely related to the surface structures of Pd-based alloy catalysts; among them, the

Plasma technology is an eco-friendly way to modify or fabricate carbon-based materials (CBMs) due to plasmas' distinctive abilities in tuning the surface physicochemical properties by implanting functional groups or incorporating heteroatoms into the surface without changing the bulk structure. However, the mechanisms of functional groups formation on the carbon surface are still not clearly explained because of the variety of different discharge conditions and the complexity of plasma chemistry. Consequently, this paper contains a comprehensive review of plasma-treated carbon-based materials and their applications in environmental, materials, and energy fields. Plasma-treated CBMs used in these fields have been significantly enhanced in recent years because these related materials possess unique features after plasma treatment, such as higher adsorption capacity, enhanced wettability, improved electrocatalytic activity, etc. Meanwhile, this paper also summarizes possible reaction routes for the generation of functional groups on CBMs. The outlook for future research is summarized, with suggestions that plasma technology research and development shall attempt to achieve precise control of plasmas to synthesize or to modify CBMs at the atomic level.

Water gas shift Steam reforming Carbon emission reduction Hydrogen production a b s t r a c t Hydrogen has been widely considered a clean fuel of the future, with the highest mass based energy density of known fuels. Water gas shift (WGS) and steam reforming (SR) are the major reactions used for hydrogen production, and improved catalysts are essential to the future of the WGS and SR processes. Much progress in the different aspects of these fields has been made recently, which includes approaches to preparation and characterization , doping and promotion, as well as evaluation of catalysts, especially nanocatalysts. Significant improvements have been realized in increasing the stability of the catalysts, the overall conversion of raw materials, and the hydrogen production selectivity. This review aims to introduce these hydrogen production processes, to present developments in these areas, and discusses recent improvements that have made noteworthy impacts.

Keywords: Reed black liquor (RBL) Pyrolysis Fluidized bed Calcium-based zeolite Alkali recovery A B S T R A C T Fluidized bed pyrolysis is a promising technology for recovering value from reed black liquor (RBL) but it can be limited by agglomeration of the bed material and loss of fluidization. To address this challenge, laboratory experiments examined the continuous, fluidized bed pyrolysis of RBL using two different bed materials at temperatures ranging from 530 to 780 °C. Pyrolysis with silica sand as the bed material showed sintering within 120 s and loss of fluidization at a bed temperature of 680 °C. Pyrolysis with calcium-based zeolite as the bed material retained fluidization for the entire test period of 30 min at all temperatures examined. Increasing pyrolysis temperature with the calcium-based zeolite increased H 2 generation and decreased tar production, with the highest temperature examined (780 °C) providing the best performance. Fluidized bed combustion of the pyrolysis char (both at 780 °C) recovered 87% of the sodium in the RBL. Pyrolysis of RBL using fluidized bed technology with a calcium-based zeolite bed material is feasible and effective.

The CO 2 methanation is an important process in coal-togas , power-togas and CO 2 removal for spacecraft. Recently, metal-organic framework (MOF) derivatives have been demonstrated as high-performance catalysts for CO 2 upgrading processes. However, due to the high costs and low stability of MOF derivatives, it still remains challenge for the development of alternative synthesis methods avoiding MOF precursors. In this work, we present the sol-gel method for loading Ni-MOF to silica support in two-steps. Upon modifying the procedure, a more simplified one-step sol-gel method has been developed. Furthermore, the obtained Ni/SiO 2 catalyst still exhibits great catalytic performance with a CO 2 conversion of 77.2% and considerable CH 4 selectivity of ~100% during a stability test for 52 h under a low temperature of 310 • C and high GHSV of 20,000 mL⋅g − 1 ⋅h − 1. Therefore, this work provides a groundbreaking direct strategy for loading MOF derived catalysts, and might shed a light on the preparation of highly dispersed Ni/SiO 2 catalyst.

• A zeolite-supported amine adsorbent was synthesized for capturing CO 2. • Multiple amines were fixed to HZSM-5 zeolites via wet impregnation method. • The CO 2 adsorption quantity was up to 4.44 mmol/g. • Activation energy of desorption were as low as 54.27 kJ/mol. • Low desorption temperature of 83°C indicates low energy demand for CO 2 capture. A B S T R A C T Solid adsorbents were prepared by fixing amines to HZSM-5 zeolites via wet impregnation method, and the CO 2 adsorption properties were investigated in a fixed-bed adsorption system followed by the structural, thermo-dynamic and kinetic studies. The HZSM-5 with 25 in Si/Al ratio and~2.3 μm in average particle size was found to be a favourable CO 2 adsorbent support; whereby CO 2 adsorbents supporting monoethanolamine (MEA) and hydroxyethyl ethylenediamine (AEEA) exhibited good CO 2 adsorption capacities, with maximum values of 4.27 and 4.44 mmol/g being achieved, respectively. Desorption kinetics and thermodynamic studies showed that the CO 2 desorption process of AEEA loaded HZSM-5 exhibited a low activation energy of 54.27 kJ/mol. This low activation energy attributes to two possible reasons: HZSM-5 zeolite provides a large number of free H + ions, which directly participate in carbamate breakdown; HZSM-5 can also provide metal atoms (Al) that attach to the N atom of carbamate, thereby stretching the C-N bond and promoting decomposition. Furthermore, the AEEA loaded HASM-5 adsorbent has high adsorption-desorption stability in the regeneration cycle tests, revealing the energy efficiency of the CO 2 desorption process and low CO 2 capture cost.

In this study, the Powder River Basin (PRB) coal fast pyrolysis was conducted at 700°C in the atmosphere of syngas produced by CH 4-CO 2 reforming in two different patterns, including the double reactors pattern (the first reactor is for syngas production and the second is for coal pyrolysis) and double layers pattern (catalyst was at upper layer and coal was at lower layer). Besides, pure gases atmosphere including N 2 , H 2 , CO, H 2-CO were also tested to investigate the mechanism of the coal pyrolysis under different atmospheres. The pyrolysis products including gas, liquid and char were characterized, the result showed that, compared with the inert atmosphere, the tar yield is improved with the reducing atmospheres, as well as the tar quality. The hydrogen partial pressure is the key point for that improvement. In the atmosphere of H 2 , the tar yield was increased by 31.3% and the contained BTX (benzene, toluene and xylene) and naphthalene were increased by 27.1% and 133.4%. The double reactors pattern also performed outstandingly, with 25.4% increment of tar yield and 25.0% and 79.4% for the BTX and naphthalene. The double layers pattern is not effective enough due to the low temperature (700°C) in which the Ni-based catalyst was not fully activated.

Porous β-Silicon carbide (β-SiC) is an important ceramic material due to its superior properties, such as high surface area, excellent chemical and mechanical stability, and high resistance toward oxidation and corrosion. In this study, inexpensive and easily obtained corn stover and sandstone were used as the carbon and silicon sources, respectively, and porous β-SiC was effectively synthesized with a high yield. The synthesized β-SiC was characterized by XRD, Raman, SEM, TEM, and TGA, and the gaseous products were also analyzed with an integrated furnace-MS system. The results show that the produced β-SiC exhibited a nanostructure that followed the graphitic carbon template derived from the pyrolysis of the corn stover. The surface area as high as 397 m 2 /g, the pore volume of 0.4 cm 3 /g, as well as the majority pore diameters of 3−6 nm were achieved. CO and CO 2 were released during the reaction between vaporized SiO and graphite. The effect of temperature in the range of 1000 to 1700°C was also studied, and the results point to a strong dependence between the process temperature and the yield and density of β-SiC. Also, the possible mechanism of synthesized β-SiC was proposed and confirmed with experimental results. This study provides a simple and an eco-friendly carbothermal reduction approach to produce nanoporous β-SiC with agriculture waste and sandstone, which could help establish the green economy in the US.

Cost-effective CO 2 conversion to highly demanded fuels or chemicals is challenging. Accordingly, a nanos-tructured Ni/CeO 2-SGM catalyst synthesized by a simple sol-gel method was developed to make progress in this area for CO 2 methanation. CO 2 conversion reached 80.5 % and the achieved CH 4 selectivity was as high as 95.8 % even at a temperature as low as 250 ºC under a high gas hourly space velocity of 40,000 mL·g −1 ·h −1 for 106 h over Ni/CeO 2-SGM. The activity of Ni/CeO 2-SGM is 2-48 times of the state-of-the-art Ni/CeO 2 catalysts. It was found that the high-performance mainly results from a formate pathway via a *CHO intermediate along with the significant synergy of efficient dissociation of H 2 by small nickel NPs and the strong adsorption and activation of CO 2 by CeO 2 support. The findings with the performance of nanostructured Ni/CeO 2-SGM and the associated reaction mechanism, will be significantly beneficial to development of new generation of CO 2 methanation catalysts.

The aim of the present work is to provide a preliminary support and research foundation for developing integrated technology of methane dry reforming and pine wood pyrolysis to produce high value chemicals and fuels. The chemical properties of bio-oil produced by pine wood pyrolysis under traditional N 2 , H 2 , CO 2 , CH 4 atmospheres and mixtures of CH 4 and CO 2 were investigated. Experimental studies were conducted in a fixed bed reactor at a temperature of 500 C. The results show that pine wood pyrolysis under mixtures of methane and CO 2 can promote bio-oil production (0.98% increase) compared with traditional pyrolysis (under N 2). GC-MS results show that the contents of phenols and sugars in bio-oil decreased, while the amount of alcohols, aldehydes, ketones, and furans increased. NMR spectroscopy provides additional support of the results. Results indicate that bio-oil can be used as a source of value-added chemicals. High proportions of CO were obtained in the gas products from pine wood pyrolysis under CH 4 and mixtures of CH 4 and CO 2. Finally, a possible reaction pathway of pine wood pyrolysis under mixtures of methane and CO 2 is proposed. Methane bi-reforming with CO 2 and steam from pine wood pyrolysis could promote the production of high value oxygen-containing chemicals during pine wood pyrolysis under mixtures of CH 4 and CO 2 .

• "Dry amine" solid CO 2 sorbents were synthesized within 60 s. • "Dry amine" sorbents are cost-effective due to cheap support. • "Dry amine" sorbents show excellent CO 2 capture performance due to the open structure. A B S T R A C T The low cost and facile preparation of CO 2 sorbents are extremely important for the practical CO 2 capture application. In this study, we demonstrate a facile preparation of "dry amine" CO 2 sorbents through a cost-effective and environmental friendly pathway. Commercially available mass-produced SiO 2 nanoparticles were used as the support of "molecular basket" sorbents. Tetraethylenepentamine (TEPA) was quickly (60 s) loaded on the surface of SiO 2 nanoparticles through high-speed mechanical mixing (22000 rpm) method. Compared with the conventional wet impregnation method, no solvent is required. Although this new pathway is simple, timesaving, cost-effective and environmental friendly, the prepared sorbents present excellent CO 2 capture performance. The results show that with the increase of the TEPA loading, the CO 2 adsorption amount of the TEPA/SiO 2 sorbent increases first and then decreases. The 50TEPA/SiO 2 sorbent shows much higher CO 2 uptake (3.98 mmol/g) than SBA-15 based sorbent (2.45 mmol/g) prepared through the same method. And it also displays lower mass transfer resistance due to the small particle size and the open structure while 50TEPA/SBA-15 shows larger mass transfer resistance due to the channel structure. The results also show that 50TEPA/SiO 2 has good reproducibility. Due to the low cost and facile preparation, the dry amine sorbents may also show the potential application for urgent use, such as SO 2 leak or H 2 S leak.

The chemical looping ammonia generation (CLAG) of N-sorption/desorption reactions via Al-based N-carriers for producing ammonia (NH 3) (a non-carbon fuel) is thought to be an important alternative to the conventional Haber-Bosh NH 3 synthesis technology. However, the low yield of NH 3 , because of significant NH 3 decomposition at the required N-desorption temperature, inhibits the development of CLAG. Accordingly, ZrO 2 mixed AlN was designed in this study to investigate the NH 3 generation characteristics of AlN during the N-desorption process in a stationary bed reactor. The results showed that ZrO 2 can improve the formation of NH 3 because the molecular adsorption of NH 3 occurred on the ZrO 2 surface, thus preventing NH 3 from decomposing. The ZrO 2 loadings and steam concentrations in the atmosphere positively affect the yield and generation efficiency of NH 3 , while increasing the reaction temperature increased the NH 3 yield from 1.2 to 3.3 mmol, but reduced the NH 3 generation efficiency from 91.7% to 60.3%.

The use of highly alkaline water in irrigation can result in major problems for soils that have received its application. Therefore, these waters are conventionally neutralized to benign alkalinity levels through the addition of acids, which add unwanted anions, can solubilize toxic trace elements, and are dangerous to the user. Solid titanium oxyhydroxide, TiO(OH) 2 , has the potential to efficiently reduce alkalinity without the problems associated with acid additions. In this work, TiO(OH) 2 is synthesized, characterized, and evaluated for its use in alkaline water remediation. Characterization of TiO(OH) 2 was completed using inductively coupled plasma mass spectrometry (ICP-MS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. Open and closed reaction systems were used to quantify the ability of TiO (OH) 2 to remove both HCO 3 − and CO 3 2-anions from aqueous solutions. A reaction mechanism was proposed based on the results from these systems in conjunction with an attenuated total reflectance Fourier-transform infrared (ATR-FTIR) analysis of the aqueous interfacial species.