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Title: Methanol conversion to hydrocarbons via acidic catalysts
Author: Liu, Bonan
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2016
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Methanol has long been advanced as a high-energy-density, widely-obtained (from non-oil sources such as coal, and biomass) material with potential as a replacement for the limitedly-distributed, finite-in-current-storage oil resources. Given the fact that effective methanol conversion has been observed over the acidic, zeolite based catalytic materials, e.g. H-ZSM-5, since the 1970s, it is almost certain that extra catalytic properties, such as an enhanced C-H bond activation, govern by the introduced non-zeolitic promoters, e.g. metal oxide species, could further modify the reaction pathways, with potentially-achievable, lower energy costs, higher selectivity (or yields) to many valuable hydrocarbon products (e.g. olefins) and other benefits. On the other hand, a big step is to successful convert the laboratory achievements, e.g. a selected good performance zeolite sample, into the larger-scale applications. Such a process requires the involvement of catalyst binders, and when zeolite particle comes to the nano-scale, the corporation of binder phases, e.g. Al2O3, with the parent nano zeolite plays the most important role in determining the following methanol conversion. Another critical issue is the binder-incorporated, shaped zeolite catalysts would be better tested in larger reactors which are not often seen in the regular laboratory, and the scale-up also increases the research budgets. It should be mentioned that catalyst deactivation is another crucial limitation in this research area; particularly, the reaction formed cokes especially the higher-density, and deeply dehydrogenated graphitized compounds deopsiting deeply inside the zeolite cavities/channels give many difficulties not only in the effective methanol conversion but also in detecting and measuring their quantity and compositions. This thesis aims to help in solving the above mentioned challenges in an effective methanol catalytic conversion, and can be accordingly divided into 3 aspects: 1) a method to further improve the C-H bond activations for higher olefin and aromatic yields, via modification of H-ZSM-5 (Si/Al=25, industrial) with MoO3 promoters, prepared at a lower-than-usual temperature of 400 °C (routinely 500 °C or higher temperatures are employed for the calcination of metal oxide modified zeolites); 2) an attempt to scale up the laboratory methanol-to-hydrocarbon reaction, obtained over Al2O3 incorporated nano H-ZSM-5 samples (the parent nano zeolites have Si/Al ratios of 20, 60 and 120), with a customized larger fixed-bed reactor that allows catalyst loadings of 20g packed in the shaped forms; 3) a technique based on microwave perturbation measurements in a resonant cavity, inside which coked zeolite samples are analyzed, and different coking levels as well as coke compositions are evaluated based on the sample dielectric loss values that can be calculated from the measured perturbation data. Our efforts herein are made for the soul of "Science should be applied", for a sustainable future, in a great certain to be sparked by the utilization of methanol in the industries.
Supervisor: Edwards, Peter P. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available