Heterogeneous Catalysis

Surface science has evolved from being a sub-field of chemistry or physics, and has now established itself as an interdisciplinary topic. Knowledge has developed sufficiently that we can now understand catalysis from a surface science perspective. No-where is the underpinning nature of surface science better illustrated than with nanoscience.

Now in its third edition, this successful textbook aims to provide students with an understanding of chemical transformations and the formation of structures at surfaces. The chapters build from simple to more advanced principles with each featuring exercises, which act not only to demonstrate concepts arising in the text but also to form an integral part of the book, with the last eight chapters featuring worked solutions.

TiO 2 is an effective and well-known photocatalyst for water and air purification, but its practical applications in visible light-assisted chemical reactions are hindered mainly by its poor visible light absorption capacity. Nitrogen-doped TiO 2 (N-doped TiO 2) has attracted considerable attention as a photocatalyst, and rapid progress has been made in enhancing the photocatalytic efficiency of TiO 2 under visible light irradiation. N-doped TiO 2 exhibits broad absorption in the visible region, which can allow the utilization of a large part of the solar spectrum. This might be useful for environmental and energy applications, such as the photocatalytic degradation of organic pollutants, solar cells, sensors, and water splitting reactions. This review focuses on the major developments in the synthesis of N-doped TiO 2 and its possible applications in the photocatalytic degradation of organic pollutants and environmental remediation under visible light irradiation.

Highly selective synthesis of diphenylmethane (DPM) was carried out by Friedal–Crafts benzylation of benzene using benzyl chloride (BC) as alkylating agent in the presence of a flow of nitrogen under liquid phase reaction conditions over novel mesoporous SO42−/Al-MCM-41 catalysts with different Si/Al ratios. For these reactions, the influences of various reaction parameters, such as different catalysts, reaction temperature, time, mmol

This paper presents the implementation of the recent methodology called Adaptable Time Warping (ATW) for the automatic identification of mixture of crystallographic phases from powder X-ray diffraction data, inside the framework of a new integrative platform named hITeQ. The methodology is encapsulated into a so-called workflow, and we explore the benefits of such an environment for streamlining discovery in R&D.

Ketoprofen is a widespread non-steroidal anti-inflammatory agent used in treatment of acute pain and chronic arthritis. On the other hand, isoquinoline alkaloids are very well known with their wide range of biological activities. From this point of view it is of interest to us to obtain new isoquinolines containing a ketoprofen residue in their structure as new substances with potential biological activity. To estimate general efficacy and safety of the newly obtained compounds, their biological potential has been evaluated.

ABSTRACT  Stable, active, and highly selective bifunctional Ni/Al-MCM-41 catalysts were developed for the one-pot synthesis of menthols from citral. The liquid-phase hydrogenation of citral to citronellal was studied on silica-supported noble (Pt, Pd, Ir) and nonnoble (Ni, Co, Cu) metals. It was found that citronellal is selectively formed at the beginning of the reaction only on Pd and Ni catalysts. The consecutive ene-cyclization of citronellal to isopulegols was investigated on solid acids containing exclusively Lewis (ZnO/SiO2) or strong Brönsted (CsHPA) acid sites, and also on catalysts containing both Lewis and Brönsted acid sites of either strong (zeolites, SiO2–Al2O3) or moderate (Al-MCM-41) strength. The isopulegol formation rate was higher on samples exhibiting dual Lewis/Brönsted acidity, such as SiO2–Al2O3, Al-MCM-41, and zeolite HBEA. Based on these previous results, bifunctional catalysts containing Pd or Ni supported on SiO2–Al2O3, Al-MCM-41, or zeolite HBEA were prepared and tested for citral conversion to menthols. The catalyst stability and the effect of hydrogen pressure and metal loading on menthol productivity were also investigated. The best catalyst was Ni(8%)/Al-MCM-41, which yielded more than 90% menthols at 2026.0 kPa and showed no significant deactivation after two consecutive catalytic tests.

The work describes the results on the hydrogenation of the 2-butyne-1,4-diol (BYD) to 1,4-butanediol (BAD) over both slurry and particulate Raney nickel catalysts (Ra Ni) in batch and in a fixed bed reactor system. The detailed study on the kinetics of the reaction obtained in batch conditions revealed the existence of four stages in the overall hydrogenation network. In the first region, A, the starting BYD produces exclusively cis-2-butene-1,4-diol (cis-BED) and to a lesser degree the respective 4-hydroxybutanal (γ-HALD). In the second region, B, the cis-BED takes part in three parallel reactions of hydrogenation to BAD, isomerization to trans-2-butene-1,4-diol (trans-BED), and the formation of additional γ-HALD. In the third region, C, the trans-BED is mostly engaged in further hydrogenation to BAD, and surprisingly, starts producing the main byproduct, n-butanol (BOL). In the last kinetic region, D, the accumulated 4-hydroxybutanal is slowly hydrogenated to BAD. A completely different reaction profile is observed when the hydrogenation is carried out in an up-flow mode in a fixed bed system. The most important factors controlling the selectivity to BAD are the temperature, the contact time, and the pH of the liquid feed. It is also found that both the surface area of the catalyst and the presence of properly selected promoters, introduced into the Ra Ni system, can lead to a drastic reduction in the level of BOL and can virtually eliminate the formation of the second byproduct, 2-(4-hydroxybutoxy) tetrahydrofuran (HBOTHF).

Sulfate–zirconia catalysts were prepared via the colloidal-sol–gel method using ZrOCl2as precursor. After precipitation and washing, the solids were peptized with a 1 : 1 mixture of CH3COOH and H2SO4. The promoters were introduced as gallium, indium, or thallium nitrates into the solution containing the zirconium sols. After a gel formation period, the samples were dried and calcined. The catalysts were

Carbon nanotubes (CNTs) are currently attractive material for a diverse range of applications because of their extraordinary mechanical and electrical properties. The present study is aimed to synthesize carbon nanotubes by Catalytic chemical vapor deposition (CCVD) and effect of catalyst loading on the carbon deposition. CCVD is one of the best methods to produce carbon nanotubes (CNTs) in large scale and high quality. In this paper, we synthesized the carbon nanotubes by combination of acetylene and LPG as carbon sources and Fe–Co/Al2O3 as a catalyst. The synthesis was carried out at 700 °C in quartz reactor for 30 min. The obtained CNTs were characterized by scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and X-ray Diffraction (XRD).

Au/Mg(OH)2 catalyst was modified with different amounts of ascorbic acid. After dehydration at 350°C, in various atmospheres, the modified Au/MgO catalysts were characterized and tested in the oxidation of CO. It has been shown for the first time that at high CO pressure supported gold chemisorbs CO and the apparent gold dispersion can be determined. The oxidation of CO was

The hydrogenation of maleic acid was investigated using a bimetallic Ru–Re/C catalyst powder in a semi-batch stirred slurry reactor with the main objective of developing a kinetic model that would provide reliable predictions of the observed reactant and product ...

The effect of temperature in the 293-473 K range, on the secondary electron emission (SEE) yield of single crystal and polycrystalline diamond film surfaces is reported. For the polycrystalline films the SEE yield was found to decay as function of electron irradiation dose while for the single crystal an increase occurs first, followed by a decrease. For both surfaces, the

The conditions for preparation of high surface area zirconia were studied. Samples were prepared by precipitation from aqueous solutions of zirconium chloride with ammonium hydroxide. The order of addition of the reactants was found to affect the surface area. Digestion of the hydrous zirconia is the key to high surface area zirconia without the necessity of adding other oxides or dopants. Both the temperature and the time of digestion are important parameters. Zirconia with surface area in excess of 220 m2/g after calcination at 500°C have been obtained. The materials maintained a surface area of >90 m2/g even after heat treatment at 900°C for 12 h. In addition, digestion led to the formation of the tetragonal allotrope of zirconia. Samples which had been digested for long times at 100°C are tetragonal and maintain this phase up to 1000°C. The effects of digestion seems to be related to a phase transformation of the hydrous precursor at around 80°C. A mechanism based on defect density is postulated to explain the phase stability.

Abstract
Copper-catalyzed cross-coupling reactions offer a powerful tool for the formation of carbonheteroatom
bonds. Copper catalysis has an indisputable advantage over the other catalytic
systems due to its low cost and the use of readily accessible and stable ligands. Among the
various copper-catalyzed coupling reactions, C-S bond forming reactions have gained much
attention due to its applications in the synthesis of molecules having biological and
pharmaceutical impact. This review illustrates the current strategies and applications of Cu-catalyzed
C-S cross coupling reactions.