Sulfonic acid-functionalized hierarchical SAPO-34 (S 1 -SAPO-34-SO 3 H) was prepared by post-grafting 3-mercaptopropyltriethoxysilane, and the sulfonic acid group was then oxidized by H 2 O 2 . The obtained catalysts were characterized by XRD, SEM, FTIR, TG, nitrogen adsorption, XRF, and acid–base titration. The acidity of the modified SAPO-34 increased, which confirmed the success of grafting. The catalytic properties during the dehydration of fructose to 5-hydroxymethylfurfural (5-HMF) were investigated. The yield of 5-HMF was up to 72%, and a 34% increase was found compared with the case of SAPO-34. The findings were discussed and attributed to the synergistic effects caused by both the acid groups and the mesopores. More basic investigations with regard to the conditions, including the reaction time, temperature, solvent, load and regeneration, are needed.
Hierarchical SAPO-34 aggregates were hydrothermally synthesized with the assistance of organosilane N-[3-(Trimethoxysilyl)propyl]ethylenediamine (TPED), during which the morpholine was used as the template. The resultant products were characterized by XRD , SEM, ICP-OES, NH 3 -TPD, N 2 adsorption-desorption and TGA , and a possible formation mechanism was proposed. As the amount of added TPED varies, the morphologies, compositions and acid properties of the resultant hierarchical SAPO-34 aggregates differ. The hierarchical SAPO-34 aggregates possessed higher external surface areas, lower Si content, weaker strength and lower concentration in the strong acid sites than the conventional SAPO-34. The investigation of formation process showed that the addition of the TPED had a pivotal role for the formation of hierarchical SAPO-34 aggregates. Compared to conventional SAPO-34, the hierarchical SAPO-34 aggregates exhibited a significant improvement in methanol to olefin reaction (MTO) reactions due to their hierarchical structure and mild acid properties.
Wenwen Cong,Changyou Xu,Yahang Mu,Qiang Li,Liancheng Bing,Fang Wang,Dezhi Han,Guangjian Wang
In this work, hierarchical SAPO-34 supported PtCo bimetallic catalysts with different Pt/Co ratios were prepared by impregnation method. The obtained PtCo/SAPO-34 catalysts displayed high catalytic activities and durability for the dehydrogenation of ammonia borane (AB). Among them, Pt 1 Co 5 /SAPO-34 catalyst delivered the highest hydrogen generation activity with a turnover frequency (TOF) of 262 mol H 2 ( mol Pt ∙ min ) − 1 at 303 K as well as excellent catalytic activity in catalytic hydrogenation of 4-nitrophenol (4-NP) by coupling with hydrolytic dehydrogenation of AB, due to the electron interaction of Pt and Co in PtCo alloy and the high metal dispersion and exposure of Brønsted acidic sites on SAPO-34 support. Moreover, it is noteworthy that the prepared Pt 1 Co 5 /SAPO-34 catalyst also exhibited superior recycle stability, with 81% of the initial TOF value after five runs of hydrolysis reaction.
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