A novel, shape-selective H-MCM-22/MCM-41 composite catalyst: Synthesis, characterization and catalytic performance

Catalytic upgrading of fast pyrolysis biomass vapors over fresh, spent and regenerated ZSM-5 zeolites

“…However, this acid catalyzed transformation process usually results in polymerization of oxygenates and formation of large molecules (known as "coke") which remain trapped and covered on the surface of catalysts [12][13][14]. Typically, biomass CFP technique causes a significant coke yield with a consequence of pore blockage and fast deactivation of catalysts, thus preventing the subsequent shape-selective reactions.…”

Role of complex equilibrium in the shape-selective performances of MgO/MCM-22 catalysts prepared by complexing impregnation

“…However, the selectivity for p-xylene over parent MCM-22 zeolite is merely close to the equilibrium composition of xylene isomers (about 23%) [4]. Measures were taken to modify the acidity and structure of MCM-22 zeolite in order to promote the p-xylene selectivity [5][6][7][8][9]. We have previously reported the selective synthesis of p-xylene by alkylation of toluene with dimethyl carbonate (DMC) over MgO modified MCM-22 prepared by general impregnation method [10], in which high selectivity for p-xylene (~65.9%) was observed over the 15% MgO/MCM-22 catalyst, but catalytic activity was rather poor.…”

Micro/Mesoporous Zeolitic Composites: Recent Developments in Synthesis and Catalytic Applications

“…Moreover, a comparable 2,6-DIPN/2,7-DIPN ratio between the parent MOR and Recry-MOR confirms that the intrinsic high shape-selectivity of MOR for 2,6-diisopropylnaphthalene is maintained (Figure 12b). Another advantage of MZC catalysts in alkylation was reported by Xue et al [42]. The authors developed H-MCM-22/MCM-41 composites by overgrowing of MCM-41 over the external surface of H-MCM-22 via direct synthesis and tested the resulting catalysts in alkylation of toluene with dimethyl carbonate to p-xylene.…”

“…The micro/mesoporous structure of ZSC composites is well maintained even after steaming at 800 °C for 24 h while their acidic properties and pore accessibility are considerably improved as proved by gas phase cracking of cumene and TIPB as model compounds (Figure 4). An alternative route is to add well-defined zeolite crystals to the synthesis mixture of the mesoporous material which provides more precise control of zeolite phase and mesoporous phase distribution [31,[42][43][44][45][46][47][48][49]. By this way, a variety of composites such as Beta/TUD-1 [31], MCM-22/MCM-41 [42], Silicalite-1@SBA-15 [43], Y/MCM-48 [47] have been synthesized under different synthesis conditions.…”

“…The mesoporous silica shell with large surface area and pore channels facilitates molecular diffusion, enhancing the accessibility of acid sites of ZSM-5. This leads to high methanol conversion and propene selectivity even though the Another advantage of MZC catalysts in alkylation was reported by Xue et al [42]. The authors developed H-MCM-22/MCM-41 composites by overgrowing of MCM-41 over the external surface of H-MCM-22 via direct synthesis and tested the resulting catalysts in alkylation of toluene with dimethyl carbonate to p-xylene.…”