Improved performance of naptha reforming process by the use of metal zeolite composite catalysts

Naphtha reforming catalysts have long been used in the petroleum refinery industry. In spite of their good performance, refineries, driven by the demand for high octane fuels, have been looking for ways of improving reformer performance by either enhancing the octane number of the product or lengthening the catalyst life, i.e., decreasing coke rate. A potential way of meeting these goals would be an improvement of catalytic properties of the reforming catalysts by the addition of zeolites. With this concept in mind, the n-heptane reforming over Pt-Re/AlO and with the addition of different zeolite structures has been extensively studied under deactivation conditions. Factors such as the amount, nature, acidity and mode of zeolite addition were extensively investigated

Mechanical depolymerisation of acidulated cellulose: understanding the solubility of high molecular weight oligomers

Water soluble oligomers of cellulose were produced by milling acidulated microcrystalline cellulose. Acids with low pKa were found to be more effective for the treatment. The yield of water soluble fraction was proportional to the increasing severity of milling or the acid amount. Soluble oligomers were found to have an average degree of polymerisation of ∼7 monomer units. High resolution NMR spectroscopy was used to determine the chemical structures of soluble oligomers. It was found that branched oligomers with α (1 → 6) linkages were formed, which increased their solubility in water and reduced the generation of monomers and dimers which may degrade during milling or subsequent hydrolysis-hydrogenation. The soluble oligomers showed excellent reactivity towards hydrolysis-hydrogenation in the presence of bi-metallic Ni-Pt/alumina catalyst. High yields (∼90%) of sorbitol and mannitol were obtained with only 1 h of reaction time

A review of catalytic hydrogen production processes from biomass

Hydrogen is believed to be critical for the energy and environmental sustainability. Hydrogen is a clean energy carrier which can be used for transportation and stationary power generation. However, hydrogen is not readily available in sufficient quantities and the production cost is still high for transportation purpose. The technical challenges to achieve a stable hydrogen economy include improving process efficiencies, lowering the cost of production and harnessing renewable sources for hydrogen production. Lignocellulosic biomass is one of the most abundant forms of renewable resource available. Currently there are not many commercial technologies able to produce hydrogen from biomass. This review focuses on the available technologies and recent developments in biomass conversion to hydrogen. Hydrogen production from biomass is discussed as a two stage process - in the first stage raw biomass is converted to hydrogen substrate in either gas, liquid or solid phase. In the second stage these substrates are catalytically converted to hydrogen.Hydrogen Production Biomass Gasification Pyrolysis Aqueous Phase Reforming

Transfer hydrogenation of cellulose-based oligomers over carbon-supported ruthenium catalyst in a fixed-bed reactor

Ru supported on activated carbon was found to be active for the transfer hydrogenation of cellulose oligomers, which were produced by the milling of acidulated microcrystalline cellulose. A C sugar alcohol yield of 85 % was obtained in less than 1 h reaction time in a batch reactor. Optimum reaction conditions for transfer hydrogenation were determined as 180 °C and a pH above 2.2 using glucose as a substrate. Use of deuterium as a marker established that direct transfer of hydride species from 2-propanol to glucose occurs through the dihydride mechanism. Formation of molecular hydrogen from 2-propanol dehydrogenation was found to be a side reaction, with little influence on the glucose hydrogenation step. Conversion of cellulose oligomers to hexitols was also achieved in a continuous flow fixed-bed reactor with 36.4 % yield at a liquid hourly space velocity of 4.7 h. The catalytic activity did not decrease even after 12 h of the onstream reaction. Fix that bed: The catalytic conversion of cellulose to sugar alcohols in high yield in a continuous flow fixed-bed reactor through hydrolytic transfer hydrogenation is described. Ru supported on activated carbon catalyses direct hydrogen transfer from 2-propanol to glucose without the involvement of hydrogen gas