Catalyst

Abstract: The extensive demand for cleaner environment is forcing chemical industry to use less hazardous materials. In this regard, heteropolyacids attracted considerable amount of interest due to the less toxic behavior in addition of possessing higher acidity. Heteropoly acids have been used as catalysts for the reaction of salicylic acid with acetic anhydride. The performance of different forms of heteropoly acids in the presence of acetic anhydride as acetylating agent for acetylation of salicylic acid was compared. The best conditions were observed using Preyssler and Silica-supported Preyssler Nanoparticles as catalysts. The catalyst is recyclable and reusable.

Abstract—People today are increasingly health conscious and therefore shopkeepers tend to dispose of fatty chicken and pork skin. Chicken and pork skins thus are sources of solid waste that are usually not utilized. This paper deals with the production of useful biodiesel from utilizing the waste chicken and pork skins. Fat from the waste chicken and pork skins (sourced from local shops), was first extracted and subjected to transesterification. The products of transesterification were FAME (Fatty acid methyl esters) and glycerol. The FAME produced was tested for five parameters namely calorific value, pour point and cloud point when compared to ASTM E2515-11 standard values. Comparison of the obtained values of the five parameters with the standard values for diesel was performed to determine the viability of the biodiesel produced. The results of this experiment showed that the calorific values of FAME produced from chicken skin and pork skin fat were close to that of petroleum de...

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 potential eco-toxicity of nanosized titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) water suspensions was investigated using Gram-positive Bacillus subtilis and Gram-negative Escherichia coli as test organisms. These three photosensitive nanomaterials were harmful to varying degrees, with antibacterial activity increasing with particle concentration. Antibacterial activity generally increased from SiO2 to TiO2 to ZnO, and B. subtilis was most susceptible to their effects. Advertised nanoparticle size did not correspond to true particle size. Apparently, aggregation produced similarly sized particles that had similar antibacterial activity at a given concentration. The presence of light was a significant factor under most conditions tested, presumably due to its role in promoting generation of reactive oxygen species (ROS). However, bacterial growth inhibition was also observed under dark conditions, indicating that undetermined mechanisms additional to photocatalytic ROS production were responsible for toxicity. These results highlight the need for caution during the use and disposal of such manufactured nanomaterials to prevent unintended environmental impacts, as well as the importance of further research on the mechanisms and factors that increase toxicity to enhance risk management.

This review focuses on the importance of coupling of catalytic reactions which involves dehydrogenation
and hydrogenation simultaneously and the study of catalytic materials that are designed, adopted
and/or modified for these reactions. The special features of these reactions are minimization of H2 utilization
and reduction in production cost. Structural and textural properties also play a decisive role in this kind of
coupled reactions. This particular review although not comprehensive discusses the significant progress made
in the area of coupled reactions and also helps future researchers or engineers to find out the improvements
required in areas such as advancements in catalytic material preparation, design of the new reactors and the
application of new technologies.

Fructone (2-methyl-2-ethylacetoacetate-1, 3-dioxolane), a flavouring material, has been synthesized from ethyl acetoacetate and glycol using five water-soluble Brønsted acid ionic liquids as catalysts for the first time. The used Brønsted acid ionic liquids include [Hmim]Tfa, [Hmim]Tsa, [Hmim]BF4, [Bmim]HSO4, [Bmim]H2PO4, and [Hmim]BF4 showed the highest catalytic activity for the preparation of fructone. After reaction, the product could be isolated from the reaction system automatically, and the ionic liquid could be directly reused without dehydration.