Bharat S. Rana

Aviation fuel production from lipids by a single-step route using hierarchical mesoporous zeolites†

Hierarchical mesoporous molecular sieves with tunable zeolitic crystallinity, acidity and porosity were tailored to develop a single-step process for hydroconversion of triglycerides and free fatty acids obtained from algae and Jatropha seeds. Ni-W catalyst supported on acidic zeolitic ZSM-5 support with hierarchical structure and intra-crystalline mesoporosity with composition similar to that for typical hydrocracking catalyst could yield 40–45% C9–C15 hydrocarbons and high isomerization selectivity (isomer/n-alkane, i/n ~ 2–6) from Jatropha oil. While Ni-Mo catalysts on the same support furnished 40–50% kerosene range hydrocarbons with i/n ~ 3–13. For algal oil feed hydroconversion using sulfided Ni-Mo catalyst supported on high surface area semi-crystalline ZSM-5, unexpectedly high yield of jet-fuel range hydrocarbons (77%) with moderately high isomerization selectivity (i/n = 2.5) could be obtained.

Hydroprocessing of jatropha oil and its mixtures with gas oil

Hydroprocessing catalysts, sulfided Ni–W/SiO2–Al2O3, Co–Mo/Al2O3 and Ni–Mo/Al2O3 have been developed, and their performances in hydroprocessing of jatropha oil and its mixtures with refinery gas oil compared in terms of, detailed product distribution in order to optimize the catalyst and conditions that can give maximum yield of desired transportation fuel such as diesel or kerosene (jet). C15–C18 hydrocarbon yield (diesel range) is highest (97.9%) over Ni–Mo catalyst, while it is 80.8% over Ni–W catalyst and surprisingly low (49.2%) over Co–Mo catalyst. Jatropha oil with high as well as low free fatty acid (FFA) contents could be hydroprocessed with little observable effect on reactor metallurgy. The isomers to n-paraffins (i/n) ratio is very low and different for the three types of catalysts- nearly 22–36 times higher for the hydrocracking (Ni–W) catalyst than that for the hydrotreating (Ni–Mo) catalyst. The hydrodeoxygenation pathway for oxygen removal from triglyceride is favored over the fresh Ni–Mo and Co–Mo catalysts, while decarboxylation/decarbonylation pathway is favored over the Ni–W catalyst. But, resulfidation of used Ni–Mo catalyst results in decarboxylation/decarbonylation route being slightly more favored. The yield of diesel range (250–380 °C) product during co-processing varied between 88–92% for the Ni–Mo catalyst. Hydrodesulfurization of gas oil is better during co-processing with jatropha oil. The activation energy for overall S-removal is much lower than that for overall O-removal. Densities of the products were also observed to meet the required specification.

An improved high yielding immobilization of vanadium Schiff base complexes on mesoporous silica via azide―alkyne cycloaddition for the oxidation of sulfides

Azide–alkyne [3+2] cycloaddition “click reaction” was found to be a simple yet improved approach for the efficient immobilization of oxo–vanadium(IV) tridentate Schiff base complexes to mesoporous silica via covalent attachment as it occurred under mild reaction conditions and provided high catalyst loading compared to the direct immobilization of oxo–vanadium(IV) tridentate Schiff base complex to 3-chloropropylsilyl functionalized silica support.

Hierarchical mesoporous Fe/ZSM-5 with tunable porosity for selective hydroxylation of benzene to phenol

Hierarchical mesoporous Fe–ZSM-5 zeolite with catalytically active surface Fe species is prepared by introduction of Fe3+ in the synthesis gel of mesoporous ZSM-5 and the material synthesised with the optimum Fe content and optimum porosity is highly active and selective for the hydroxylation of benzene to phenol with nitrous oxide. The porosity of the material is controlled by the synthesis gel composition (organosilane template concentration). Samples prepared at high template/Si ratio (0.11) show lower zeolitic crystallinity and lower micropore volume but higher strong acidity than the samples prepared with low template/Si ratio (0.036). Samples with very high surface area, high strong acidity, low zeolitic wall crystallinity and 0.93 wt% Fe content show 1.3 times higher phenol formation rate than a steamed H-ZSM-5 sample. Silylation of the mesoporous catalyst resulted in 2-fold increase in initial phenol formation rate compared to steamed microporous H-ZSM-5 which is attributed to improved hydrophobicity and reduced Lewis acid sites, resulting in better desorption of the phenol product from catalyst.

Development of Hydroprocessing Route to Transportation Fuels from Non-Edible Plant-Oils

Catalysts with tunable porosity, crystallinity and acidity can selectively produce aviation fuels and road transportation fuels via hydroprocessing of non-edible oils. Here we discuss several catalyst supports—mesoporous alumina, silica–alumina and hierarchical mesoporous zeolites, developed and used as support for hydroprocessing catalysts (Ni–Mo, Co–Mo, Ni–W), for the selective production of transportation fuels. These developed catalysts were used for the hydroconversion of waste cooking-oil, jatropha-oil, algal-oil and their mixtures with petroleum refinery oils. The physicochemical properties of the catalyst were tuned for optimal performance on the basis of evaluation results on high pressure fixed bed microreactors and pilot scale reactors. These studies targeted the production of transportation fuels (gasoline, kerosene and diesel) by hydroprocessing (hydrotreating or hydrocracking) renewable feed stocks or co-processing with fossil based oils. Modelling and process optimization studies for prediction of kinetic rate parameters and to know the reaction pathways for the conversion of these feed stocks to various range of hydrocarbon fuels, were also carried out. These studies provided the vital information that the reaction pathways were temperature dependent.

Hydrotreatment of renewable oils using hierarchical mesoporous H-ZSM-5 synthesized from kaolin clay

Hierarchical mesoporous ZSM-5 with tailored physicochemical properties was successfully synthesized by using kaolin clay as a cheap alumina source and organosilane as a mesopore directing agent. The synthesized material was used as a support for developing a hydroprocessing catalyst (Ni–Mo). Hydrotreatment of jatropha oil over sulfided Ni–Mo catalyst supported on the developed H-ZSM-5 was carried out. The influence of reaction conditions like temperature, pressure, and LHSV were studied in detail and the results were compared with those obtained for hydrotreatment of jatropha oil using mesoporous ZSM-5 synthesized from conventional precursors. It was observed that the C15–C18 hydrocarbon diesel yield was highest (93%) at a temperature of 375 °C, 50 bar pressure and 1.5 h−1 LHSV, while the C9–C15 hydrocarbon yield (kerosene range) was maximum (37.4%) at a temperature of 425 °C, 80 bar pressure and 0.5 h−1 LHSV. The performance of clay derived catalyst for kerosene production was comparable with that of a conventional catalyst but at higher temperature. But the clay derived catalyst showed higher and more stable activity than the conventional mesoporous zeolite. This may be attributed to milder acidity (due to alumina patches), unlike conventional mesoporous zeolite which has more isolated Al sites and hence a greater number of acid sites.