Aditya Rai

Mesoporous TUD-1 supported indium oxide nanoparticles for epoxidation of styrene using molecular O2

Activation of molecular O2 by metal or metal oxide nanoparticles is an area of recent research interest. In this work, for the first time, we report that indium oxide nanoparticles of <3 nm size dispersed on mesoporous silica (TUD-1) can activate molecular O2 and produce styrene epoxide with a selectivity of 60% and styrene conversion around 25% under mild conditions. It is found that neither indium oxide nor TUD-1 themselves respond to the styrene epoxidation reaction. The computational studies provide evidence that an oxygen molecule is highly polarized when it is located near the interface of both surfaces. The kinetic study shows that the reaction is of pseudo-first order and that the activation energy for styrene conversion is 12.138 kJ mol−1. The catalysts are recyclable for up to four regeneration steps, with the styrene conversion and styrene epoxide selectivity almost unchanged.

Indium oxide nanocluster doped TiO2 catalyst for activation of molecular O2

The In2O3 nanocluster doped faceted nanosize anatase TiO2 can activate molecular O2 for styrene epoxidation reaction. The {001} planes of anatase TiO2 are exposed for 550 °C calcined samples whereas {101} planes are predominantly observed for 450 °C calcined samples. The computational studies highlight that In2O3 is better stabilized on {001} planes of TiO2 resulting in efficient activation of molecular oxygen on In2O3 nanocluster doped {001} faceted TiO2 nanostructures. From the kinetic measurements, it is found that styrene epoxidation reaction is of pseudo-zero order and the corresponding rate constant (k) for the reaction calcined at 450 °C is 0.188 h−1 and at 550 °C it is 0.366 h−1. The activation energy for the reaction is found to be 28.44 kcal mol−1.

Co-processing of bio-oil from de-oiled Jatropha curcas seed cake with refinery gas–oil over sulfided CoMoP/Al2O3 catalyst

A sulfided cobalt–molybdenum–phosphorus/aluminium oxide (CoMoP/Al2O3) catalyst was studied in the hydroprocessing of bio-oil (BO) obtained from the pyrolysis of de-oiled Jatropha curcas seed cake. Hydroprocessing was carried out with different ratios of refinery gas oil (GO) and BO. The oxygen content in the products was reduced to trace amounts after hydroprocessing. A clear product obtained from the co-processing of BO with refinery GO contained 2–16% gasoline, 30–35% kerosene, 35–44% diesel, with 50–60% alkanes, 10–45% cycloalkanes, and 1–10% aromatics, with a negligible amount of char formed in the process. Hydroprocessing of 100% BO produced 30% kerosene and 30% diesel, together with 10% gasoline, with 15% of alkanes and 15% cycloalkanes, and 45% aromatics. A maximum amount of kerosene (41%) was obtained at 648 K and 75 bar from 100% BO, with a small amount of char (1.5%) deposited on the catalyst. In comparison, over sulfided CoMo/Al2O3 catalyst (without P promoter) only 31% of kerosene was produced, with 17% char, using similar reaction conditions.

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.

Facile conversion of levulinic acid to γ-valerolactone using a high surface area magnetically separable Ni/NiO catalyst

A study on the conversion of levulinic acid (LA) to γ-valerolactone (GVL) and methyl levulinate (ML) has been done using a high surface area Ni/NiO catalyst. The hydrogenation of levulinic acid over the Ni/NiO catalyst showed high mass activity for γ-valerolactone formation (16 mmol gcat−1 h−1) at 110 °C at 40 bar pressure. The presence of acidity effects the conversion of LA to GVL and ML. First-principles DFT calculations were used to calculate the adsorption energy and transition state for the reaction. The Ni/NiO catalyst showed 99% LA conversion and 94% GVL selectivity at 110 °C in methanol, which is higher than the reported activity of Ni-based catalysts (RANEY® Ni and Ni/Al2O3).

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.

CHAPTER 9:Process Intensification for Hydroprocessing of Vegetable Oil

Hydroprocessing of vegetable oils can be effectively done in microchannel reactors using hydroprocessing catalyst coatings. Hydroprocessing catalysts, Ni–Mo/Al2O3 and Ni–Mo/SiO2–Al2O3, during processing of vegetable oil in a microchannel reactor effectively produced more oligomerized (>C18) and heavy (C15–C18) hydrocarbon products (>95% yield). The naphtha ( 99%) is in the first 50% volume of the microchannel plate. The simulation results indicate better heat and mass transfer inside the microchannel reactor whereas a non-uniform, thermal runaway heat and concentration profile was observed in the fixed-bed reactor, which favors secondary cracking reactions.