Sirirat Jitkarnka

Valuable petrochemicals, petroleum fractions, and sulfur compounds in oils derived from waste tyre pyrolysis using five commercial zeolites as catalysts: impact of zeolite properties

Valuable petrochemicals such as benzene, toluene, and xylenes have been observed in waste tyre-derived oils, indicating that waste tyre exhibits its potential to be used for an alternative source for sustainably producing petrochemicals. However, without a catalyst, such chemicals cannot be produced in a high amount. Sulfur compounds causing environmental problems and the low quality of oils were also found in tyre-derived oils. In waste tyre pyrolysis, zeolites that have been used very often to improve the quality of oil are HZSM-5 and HY, owing to their cracking and single-ring aromatics-producing abilities. Some other zeolites have been also employed occasionally, but the effects of zeolite properties on the hydrocarbon species and sulfur compounds in oils have not been explained clearly. The objective of this work was therefore to investigate the effects of zeolite properties, that are, acidity/basicity, pore channel structure, pore size, and Si/Al ratio on hydrocarbon species in pyrolysis products, especially valuable C6–C8 petrochemicals and sulfur compounds. The oils were analyzed using SIMDIST-GC for petroleum fractions and using a GCxa0×xa0GC–TOF/MS for valuable petrochemicals and sulfur-containing compounds. The analysis of the results from using five zeolites indicated that, for high production of valuable C6–C8 petrochemicals from waste tyre pyrolysis, a catalyst must (a) possess acid sites, rather than basic ones, that have high enough strength for cracking, which can result in high production of naphtha fraction and (b) have a complex channel structure with a large enough pore size (at least ~7xa0Å) that allows molecules to stay inside at a long contact time. In addition, high acid strength is more preferred to high acid density for high production of valuable C6–C8 petrochemicals, but high acid density is more preferred for production of oil with low sulfur content.

Characteristics of catalysts for enhanced green production of distillates and chemicals in bio-oil from catalytic dehydration of bio-ethanol

The dehydration of ethanol to gasoline and C6–C8 hydrocarbons has been made possible by using a HZSM-5 zeolite due to its proper acid property and shape selectivity. HZSM-5 had been also used as a support of phosphorous- (P), antimony- (Sb), and bismuth- (Bi) oxides for ethanol dehydration, which mainly gave high gasoline in oil. Since the moderate pore size of HZSM-5 limits the production of heavier biofuels in the distillate ranges (namely, kerosene and gas oil), therefore, in this work, the zeolites, HY and HBeta, with a larger pore size were employed, aiming to produce larger hydrocarbons. HZSM-5 was also used for comparison. Moreover, Group 5A oxides (P-, Sb-, and Bi oxides) were also doped onto the zeolites at 5 wt.% of elemental loading, expectedly to further enhance the production of distillate-range products. The results from the experiments carried out at 500xa0°C showed that, regardless of the type of loaded oxides, the distillate production was primarily governed by the channel opening size of zeolites, but the yield also depended on other parameters such as acid strength, and the complexity of the pore channel. HZSM-5 tended to produce high contents of large hydrocarbons (

Synthesis and rheological properties of mesoporous nanocrystalline CeO2 via sol–gel process

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Potential of Ni supported on KH zeolite catalysts for carbon dioxide reforming of methane

C9+) whereas HBeta and HY tended to produce high amounts of C6–C8 hydrocarbons, especially benzene, and toluene. HBeta and HY gave high selectivity of p-xylene in mixed xylenes. Furthermore, oxygenates were produced in a trace amount using the parent zeolites, but their formation was significantly enhanced with using oxide-promoted catalysts, especially when HY was used as the support. In addition, Group 5A oxides doped on HBeta and HY can increase the oil yield. The content of distillates in bio-oil was also more greatly enhanced by SbxOy and BixOy than by PxOy, promoted on HBeta and HY, possibly due to the promoter loading that created new stronger Brönsted acid sites. Generally speaking, high production of distillates in bio-oil preferably requires a support that possesses high strength of Brönsted acid sites in a large channel opening with low tortuosity of channel structure. Furthermore, the selected promoter should offer a new type of acid sites on the catalyst.