Penghui Zeng

Preparation of phosphorus-modified PITQ-13 catalysts and their performance in 1-butene catalytic cracking

Abstract A series of phosphorus-modified PITQ-13 catalysts was prepared by wet impregnation of NH4H2PO4 solution into an HITQ-13 parent. The catalysts were characterized using XRD, N2 adsorption, MAS NMR and NH3-TPD. Their catalytic performance in 1-butene catalytic cracking was evaluated in a fixed fluidized bed reactor. The results showed that the crystallinity, surface area and pore volume of P-modified PITQ-13 catalysts decreased with the increasing amounts of P. The number of weak acid sites increased, whereas that of strong acidity decreased. The selectivity to propylene in 1-butene cracking reactions increased because of the decrease in strong acidity. The yield of propylene achieved 41.6% over PITQ-13-2 catalyst with a P content of 1.0 wt%, which was 5.1% greater than that achieved over HITQ-13 catalyst.

Catalytic performances of Al-ITQ-13 zeolites with different SiO 2 /A1 2 O 3 ratios in the conversion of methanol to propene

Abstract Al-ITQ-13 zeolites with different SiO2/Al2O3 molar ratios were synthesized by using seeds in the gel and characterized by XRD, SEM, N2 physisorption, MAS NMR and NH3-TPD. The effect of SiO2/Al2O3 molar ratio on the catalytic performance of Al-ITQ-13 in the conversion of methanol to propene (MTP) was investigated in a fixed-bed micro-reactor. The results showed that the Al-ITQ-13 zeolites with different SiO2/Al2O3 molar ratios are similar in their textural properties; however, the amount and strength of acid sites decrease with the increase of SiO2/Al2O3 molar ratio. Moreover, the SiO2/Al2O3 molar ratio has a significant influence on the catalytic behavior of Al-ITQ-13 in MTP. As the hydrogen transfer and aromatization reactions were suppressed over the Al-ITQ-13 zeolite with high SiO2/Al2O3 molar ratio, with the increase of SiO2/Al2O3 molar ratio, the selectivity to propene and butene is increased at the expense of the selectivity to propene; that is, with the increase of SiO2/Al2O3 molar ratio from 137 to 309, the selectivity to propene is increased from 46.04% to 55.52% and meanwhile, the propene/ethene ratio is increased from 3.39 to 6.57.

Synthesis and characterization of ZSM-5 with novel ternary-particle morphology and pore structure

ZSM-5 zeolite with novel ternary-particle morphology and pore structure was synthesized successfully using a cationic starch as the structure template. XRD confirmed that QASt-ZSM-5 zeolite was phase-pure and highly crystalline. SEM showed that QASt-ZSM-5 had novel ternary-particle morphology, the large crystals were really twinned, cube-shaped crystals of characteristic ZSM-5. Nitrogen adsorption-desorption isotherms of QASt-ZSM-5 appeared to show a more pronounced hysteresis loop and a higher adsorbed quantity of nitrogen in the higher relative pressure section. Daqing heavy oil was employed as the feedstock to evaluate the catalytic properties of QASt-ZSM-5 zeolite catalyst. The new material (QASt-ZSM-5) showed that it had a good selectivity for diesel and the yield of total light oil increased, compared with the catalytic cracking performance of ordinary ZSM-5.