Template syntheses of mesoporous carbons as catalyst support for hydrodesulfurization.

摘要

To achieve ultra-deep hydrodesulphurization (HDS) of diesel fuel without new investment in petroleum refineries, further improvement in catalysis is one of the effective approaches. The system with much higher activity and selectivity is particularly demanded for the HDS of refractory sulfuric constituents such as 4,6-dimethyldibenzothiophene (4,6-DMDBT) or 4E6MDBT. There are several advantages for carbon as catalyst support. Activated carbon-supported Mo, Co-Mo or Ni-Mo sulphide hydrodesulphurization (HDS) catalysts exhibit better activity per unit weight than their alumina-supported counterparts. However, high micro porosity, insufficient mechanical properties and low density are probably the main reasons why the carbon-supported catalysts have not been widely used.;To further evaluate the support, the research has been extended to the loading of Co/Mo to the various porous carbons obtained from our work. The evaluation of catalytic performance was conducted using various techniques including XPS and nitric oxide (NO) chemisorption. It has been found that the as-synthesized porous carbons, the one containing both micro and meso pores in particular, are, very promising as catalyst supports. This has been reflected by the fact that the catalyst supported on micro-meso porous carbon exhibits surprisingly high NO uptakes which have strong correlation with the intrinsic HDS activities. The mesoporous carbon synthesized using SBA-15/sucrose also displays higher NO uptakes than the one supported on traditional activated-carbon.;The first part of this work has focused on using zeolite as template and furfuryl alcohol (FA) as carbon source to synthesize ordered microporous carbon. Four different template/carbon-source incorporation methods were employed; and the polymerizations of FA were performed in the presence or absence of acidic catalyst. The resulting carbons displayed micro-meso porous characteristics, and no ordered microporous structure was observed. However, the resulting carbons have large BET surface area and total pore volume. It was also found that the micro-meso structures significantly facilitated the loading of active-phase in catalysts. The second part of this work dealt with using SBA-15 as template to synthesize mesoporous carbon. Furfuryl alcohol and sucrose were used as carbon sources, respectively. The syntheses started from the preparation of SBA-15; and the influence of aging temperatures on the texture of resulting carbons was also studied. The resulting carbons exhibited appropriate replica structure of SBA-15. The ratios of carbon source/SBA-15 were also varied in an attempt to establish the relationship between the dosage of carbon sources and the texture properties of the resulting carbons (BET surface area and total pore volume).