Mohit Anand

Temperature-dependent reaction pathways for the anomalous hydrocracking of triglycerides in the presence of sulfided Co–Mo-catalyst

Kinetic studies and product profiling was done to understand the anomalous cracking of jathropha oil triglycerides in the presence of sulfided Co-Mo/Al(2)O(3) catalyst. At temperatures between 320 and 340 °C, only deoxygenation and oligomerization reactions took place whereas at temperatures above 340 °C, internal conversions between the products and direct conversion to lighter and middle distillates were favored High pressures (80 bar) and H(2)/feed ratios (>1500) were necessary to minimize oligomerization of the products and to increase the lifespan of the catalyst. Lumped kinetic models were validated with experimental results. Activation energies for the formation of lighter (83 kJ/mol) and middle fractions (126 kJ/mol) were higher than those for the heavy (47 kJ/mol) and deoxygenated (47 kJ/mol) products. Jatropha oil triglycerides hydroconversion pathways were dependent on temperature and the triglycerides could be hydrocracked to lower range hydrocarbons (C5-C14) by increasing the reaction temperatures.

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.

Faceted Titania Nanocrystals Doped with Indium Oxide Nanoclusters As a Superior Candidate for Sacrificial Hydrogen Evolution without Any Noble-Metal Cocatalyst under Solar Irradiation

Development of unique nanoheterostructures consisting of indium oxide nanoclusters like species doped on the TiO2 nanocrystals surfaces with {101} and {001} exposed facets, resulted in unprecedented sacrificial hydrogen production (5.3 mmol h(-1) g(-1)) from water using methanol as a sacrificial agent, under visible light LED source and AM 1.5G solar simulator (10.3 mmol h(-1) g(-1)), which is the highest H2 production rate ever reported for titania based photocatalysts, without using any noble metal cocatalyst. X-ray photoelectron spectroscopy (XPS) analysis of the nanostructures reveals the presence of Ti-O-In and In-O-In like species on the surface of nanostructures. Electron energy-loss spectroscopy (EELS) elemental mapping and EDX spectroscopy techniques combined with transmission electron microscope evidenced the existence of nanoheterostructures. XPS, EELS, EDX, and HAADF-STEM tools collectively suggest the presence of indium oxide nanoclusters like species on the surface of TiO2 nanostructures. These indium oxide nanocluster doped TiO2 (In2O3/T{001}) single crystals with {101} and {001} exposed facets exhibited 1.3 times higher visible light photocatalytic H2 production than indium oxide nanocluster doped TiO2 nanocrystals with only {101}facets (In2O3/T{101}) exposed. The remarkable photocatalytic activity of the obtained nanoheterostructures is attributed to the combined synergetic effect of indium oxide nanoclusters interacting with the titania surface, enhanced visible light response, high crystallinity, and unique structural features.

Anomalous hydrocracking of triglycerides over CoMo-catalyst-influence of reaction intermediates.

AbstractReaction intermediates have been identified and followed to understand anomalous cracking of jathropha oil triglycerides in the presence of sulphided Co-Mo/Al2O3 catalyst. Undesirable C–C coupling reactions are favoured at temperatures between 320° and 340°C, giving waxy oligomerization products, whereas at temperatures above 340°C, direct hydrocracking of triglycerides to lighter and middle distillates were favoured. To minimize undesirable waxy oligomerization products, higher pressures (>80 bar) and higher H 2/feed ratios (>1500) were necessary. Aldol condensation and ketonization reactions between the reaction intermediates are counter-productive as they result in waxy long chain oxygenated products which tend to accumulate on the catalyst surface, choke the reactor and cause rapid catalyst deactivation. Reaction conditions have to be optimized to minimize condensation reaction during this process. ᅟUndesired C-C coupling reactions such as aldol condensation and ketonization taking place over CoMo/Al2O3 lead to competitive reactions which decrease selectivity of desired product and reduce catalyst life.

Improved hydrogenation function of Pt@SOD incorporated inside sulfided NiMo hydrocracking catalyst

A multifunctional catalyst with Pt incorporated inside sodalite cages (SOD) encapsulated in ZSM-5 supported with Ni and Mo was synthesized, characterized and evaluated as a hydrocracking catalyst for the conversion of triglycerides to kerosene and diesel. The Pt@SOD was further encapsulated inside hierarchical mesoporous ZSM-5 zeolite to prepare a bifunctional catalyst (H-ZSM-5 for acid functionality and sulfided NiMo along with Pt@SOD for hydrogenation functionality). Metal dispersion, temperature programmed reduction (TPR, H2) and temperature programmed desorption (TPD, ammonia) studies were done to evaluate the bifunctional nature of the catalyst. The sulfided NiMo-Pt@SOD-ZSM-5 catalyst showed improved catalytic activity compared to the sulfided NiMo-ZSM-5 catalyst under severe reaction conditions of low hydrogen/feed ratio. We show for the first time that it is possible to operate at low H2 concentrations during hydroprocessing of triglycerides with 99% conversion and 93% selectivity for diesel range compounds at 250 NL L−1 and 380 °C temperature. Computational studies showed that H2 molecules activated by Pt inside the sodalite cages are available for reactions outside the cages. The synthesized catalyst showed high hydrodeoxygenation activity even at lower pressure (50–60 bar) and hydrogen/feed ratios of 500–1500 NL L−1. The catalyst showed better stability against deactivation (4 times less coke deposition) than sulfided NiMo-ZSM-5 catalyst during a continuous run due to the presence of Pt@SOD.

Kinetics and computational fluid dynamics study for Fischer–Tropsch synthesis in microchannel and fixed-bed reactors

The effect of operating conditions on the hydrocarbon yield distribution during Fischer–Tropsch synthesis (FTS) in a microchannel reactor was studied. A power law-based kinetic model was developed for the first time in microchannel and fixed bed reactors for FTS reactions. The activation energy calculated was 90.16 kJ mol−1 and 106.17 kJ mol−1 in the microchannel reactor and fixed bed reactor, respectively. In a single pass run, the CO conversion obtained in the microchannel reactor was more than 92%, while it was 70% in the fixed bed reactor over the same catalyst. The concentration and temperature profile are predicted in both fixed bed and microchannel reactors. As expected, there was no axial concentration gradient observed in the microchannel reactor. Under adiabatic conditions, kinetic and thermodynamic study simulations showed an increase in reactor temperature from 598 K to 639 K in the microchannel reactor and 598 K to 607 K in the fixed bed reactor. The heat produced per unit volume of the microchannel reactor is higher due to a higher rate of the reaction compared to that in the fixed bed reactor.

Aviation Biofuels Through Lipid Hydroprocessing

Hydroprocessing routes to producing alternative aviation fuels have become a well-established technology, though not yet cost-competitive due to the higher cost of animal- and plant-derived triglycerides/lipids. This chapter describes academic and technological advances for the processing of lipids obtained from various sources via hydroprocessing routes to produce biofuels. The effect of different catalytic systems, operating parameters, reaction pathways, and kinetics involved in the hydroprocessing of lipids is also described. Among different catalysts reported and discussed, the sulfided mesoporous catalysts with moderate acidity and higher surface area are similar to currently used hydrocracking catalysts, and are easier to retrofit in the current refinery infrastructure for large-scale production, even under co-processing conditions. In addition to reaction chemistry and conditions, this chapter also discusses technical challenges, such as the high exothermicity observed during the reaction, pretreatment strategies for increased catalyst life, recycled gas purification issues, and regular feedstock availability, etc., that must be overcome for commercialization of this process for production of aviation biofuels.