Glycerol conversion in the presence of carbon dioxide on alumina supported nickel catalyst

Advanced zeolite and ordered mesoporous silica-based catalysts for the conversion of CO2 to chemicals and fuels

For many years, capturing, storing or sequestering CO₂ from concentrated emission sources or from air has been a powerful technique for reducing atmospheric CO₂. Moreover, the use of CO₂ as a C1 building block to mitigate CO₂ emissions and, at the same time, produce sustainable chemicals or fuels is a challenging and promising alternative to meet global demand for chemicals and energy. Hence, the chemical incorporation and conversion of CO₂ into valuable chemicals has received much attention in the last decade, since CO₂ is an abundant, inexpensive, nontoxic, nonflammable, and renewable one-carbon building block. Nevertheless, CO₂ is the most oxidized form of carbon, thermodynamically the most stable form and kinetically inert. Consequently, the chemical conversion of CO₂ requires highly reactive, rich-energy substrates, highly stable products to be formed or harder reaction conditions. The use of catalysts constitutes an important tool in the development of sustainable chemistry, since catalysts increase the rate of the reaction without modifying the overall standard Gibbs energy in the reaction. Therefore, special attention has been paid to catalysis, and in particular to heterogeneous catalysis because of its environmentally friendly and recyclable nature attributed to simple separation and recovery, as well as its applicability to continuous reactor operations. Focusing on heterogeneous catalysts, we decided to center on zeolite and ordered mesoporous materials due to their high thermal and chemical stability and versatility, which make them good candidates for the design and development of catalysts for CO₂ conversion. In the present review, we analyze the state of the art in the last 25 years and the potential opportunities for using zeolite and OMS (ordered mesoporous silica) based materials to convert CO₂ into valuable chemicals essential for our daily lives and fuels, and to pave the way towards reducing carbon footprint. In this review, we have compiled, to the best of our knowledge, the different reactions involving catalysts based on zeolites and OMS to convert CO₂ into cyclic and dialkyl carbonates, acyclic carbamates, 2-oxazolidones, carboxylic acids, methanol, dimethylether, methane, higher alcohols (C₂₊OH), C₂₊ (gasoline, olefins and aromatics), syngas (RWGS, dry reforming of methane and alcohols), olefins (oxidative dehydrogenation of alkanes) and simple fuels by photoreduction. The use of advanced zeolite and OMS-based materials, and the development of new processes and technologies should provide a new impulse to boost the conversion of CO₂ into chemicals and fuels.

Statistical Optimisation using Taguchi Method for Transesterification of Reutealis Trisperma Oil to Biodiesel on CaO-ZnO Catalysts

Optimisation of biodiesel production from non-edible Reutealis Trisperma oil (RTO) was investigated using Taguchi method. Biodiesel was produced via consecutive esterification and transesterification reactions. Esterification of RTO was carried out using acid catalyst to decrease the amount of free fatty acid from 2.24% to 0.09%. Subsequent transesterification of the treated oil with methanol over a series of CaO-ZnO catalysts was optimized based on the L9 Taguchi orthogonal approach. The optimization parameters are Ca/Zn ratio (0.25, 0.5, and 1), methanol/oil ratio (10, 20, and 30) and reaction time (0.5, 1, and 2 h). CaO-ZnO catalysts at variation of Ca/Zn ratios were prepared using co-precipitation method and characterized using XRD, SEM, TEM, and FTIR analysis. The amount of methyl ester yield was used as the response parameter in the S/N ratio analysis and Analysis of Variance (ANOVA). The optimum parameter for RTO transesterification to biodiesel was determined at Ca/Zn ratio of 1, methanol oil ratio of 30 and reaction time for 2 h. Transesterification under these optimized parameter generated 98% of biodiesel yield, inferring the validity of the statistical approach. Furthermore, ANOVA analysis also confirmed that all the parameters were significantly contributed at approximately equal percentage towards the amount of biodiesel. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Versatile Coordination Polymer Catalyst for Acid Reactions Involving Biobased Heterocyclic Chemicals

The chemical valorization/repurposing of biomass-derived chemicals contributes to a biobased economy. Furfural (Fur) is a recognized platform chemical produced from renewable lignocellulosic biomass, and furfuryl alcohol (FA) is its most important application. The aromatic aldehydes Fur and benzaldehyde (Bza) are commonly found in the slate of compounds produced via biomass pyrolysis. On the other hand, glycerol (Gly) is a by-product of the industrial production of biodiesel, derived from fatty acid components of biomass. This work focuses on acid catalyzed routes of Fur, Bza, Gly and FA, using a versatile crystalline lamellar coordination polymer catalyst, namely [Gd(H4nmp)(H2O)2]Cl·2H2O (1) [H6nmp=nitrilotris(methylenephosphonic acid)] synthesized via an ecofriendly, relatively fast, mild microwave-assisted approach (in water, 70 °C/40 min). This is the first among crystalline coordination polymers or metal-organic framework type materials studied for the Fur/Gly and Bza/Gly reactions, giving heterobicyclic products of the type dioxolane and dioxane, and was also effective for the FA/ethanol reaction. 1 was stable and promoted the target catalytic reactions, selectively leading to heterobicyclic dioxane and dioxolane type products in the Fur/Gly and Bza/Gly reactions (up to 91% and 95% total yields respectively, at 90 °C/4 h), and, on the other hand, 2-(ethoxymethyl)furan and ethyl levulinate from heterocyclic FA.

Adsorption desulphurisation of dimethyl sulphide using nickel-based Y zeolites pretreated by hydrogen reduction

A series of nickel-modified Y zeolites were prepared for the adsorption of dimethyl sulphide (DMS) in liquid hydrocarbon streams. The adsorption desulphurisation performance was investigated under ambient conditions of nickel-based adsorbents developed by the liquid-phase ion exchange (LPIE) method and the incipient wetness impregnation (IWI) method with and without the ultrasonic aid technique. It was found that the nickel-modified Y zeolite prepared by the IWI method with the ultrasonic aid technique with hydrogen reduction demonstrated a high sulphur capacity of 69.9 mg of S per g of sorbent at a break-through sulphur level of 10 μg g