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Catalytic pyrolysis behavior of synthesized microporous catalysts (conventional Zeolite Socony Mobil-5 (C-ZSM-5), highly uniform nanocrystalline ZSM-5 (HUN-ZSM-5) and β-zeolite), Mesoporous catalysts (highly hydrothermally stable Al-MCM-41 with accessible void defects (Al-MCM-41(hhs)), Kanemite-derived folded silica (KFS-16B) and well-ordered Al-SBA-15 (Al-SBA-15(wo)) were studied with waste polyethylene (PE) and polypropylene (PP) mixture which are the main constituents in municipal solid waste. All the catalysts were characterized by Brunauer-Emmett-Teller (BET), X-ray powder diffraction (XRD), and NH3-temperature programmed desorption (TPD). The results demonstrated that microporous catalysts exhibited high yields of gas products and high selectivity for aromatics and alkene, whereas the mesoporous catalysts showed high yields of liquid products with considerable amounts of aliphatic compounds. The differences between the microporous and mesoporous catalysts could be attributed to their characteristic acidic and textural properties. A significant amount of C2-C4 gases were produced from both types of catalysts. The composition of the liquid and gas products from catalytic pyrolysis is similar to petroleum-derived fuels. In other words, products of catalytic pyrolysis of plastic waste can be potential alternatives to the petroleum-derived fuels.

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A mechanism involving cooperative hydrogen bonds for ionic liquid-catalyzed biodiesel production was proposed and validated by kinetic data.

Brønsted acidic ionic liquids (BAILs) can play a dual role, as a solvent and as a catalyst, in many reactions. However, molecular details of the catalytic mechanism are poorly understood. We present here a density functional theory (DFT) study for the catalytic mechanism of the transesterification of methyl ester (ME) with trimethylolpropane (TMP), in the presence of three representative BAILs, namely, N-methylimidazole-IL, pyridinium-IL, and triethylamine-IL. The deprotonation of the BAIL cation and the transesterification step are investigated. Key inter- and intra-molecular hydrogen bonds (HBs) that govern the catalytic performance of BAILs were identified and analyzed using natural bond orbital (NBO) and atoms in molecule (AIM) methods. For the deprotonation of BAILs, it was found that the intermolecular O-HO HB between the hydroxyl group of TMP and the oxygen of the sulfonic group of BAIL was indispensable for proton transfer. DFT computed free energy barriers for the transesterification step are in excellent agreement with the experimental results only after taking into account the BAIL cation-anion interaction in terms of HBs in which the O-HO between the hydroxyl group of the anion and the oxygen of the sulfonic group of the cation was the strongest HB, suggesting the role of the anion in governing the catalytic activity of BAILs. The existence of the HBs suggested by DFT calculations was further validated using in situ FTIR experiments/ATR-FTIR.