We report a ZSM-5 based catalyst with surface modification of SiO2 to increase the selectivity of para-xylene (PX) in xylene (X) in the methanol-to-aromatics process. The effect of acid strength and acid amount in HZSM-5, Zn/P/ZSM-5, and Zn/P/Si/ZSM-5 on the catalytic performance, including methanol conversion, aromatic yield, and PX selectivity, were studied. The total acid strength and acid amount of the catalyst were crucial for high methanol conversion (around 100%) and high yield of aromatics (>60%), whereas weak external acid sites present in a small amount played an important role in increasing the PX selectivity (in the X isomers) from the usual 23–24% to 89.6%. The results validated the use of a catalyst having a core with strong acid sites in a large amount and an external shell with weak acid sites in a small amount. The contribution of the external surface reaction, including alkylation, isomerization, and dealkylation, to the PX selectivity was evaluated by using PX or ortho-X separately as f...

Increasing para-Xylene Selectivity in Making Aromatics from Methanol with a Surface-Modified Zn/P/ZSM-5 Catalyst

Conversion of methanol to aromatics in fluidized bed reactor

Bayberry-like ZnO/MFI zeolite as high performance methanol-to-aromatics catalyst

The aromatization performance of cofeeding n- butane with methanol was investigated in a fixed bed reactor over a Zn loaded ZSM-5/ZSM-11 zeolite. Coke deposited on the catalyst was characterized by TG, TPO, FTIR and Raman technique. During the 48 h life-test under the conditions of 510 °C, 0.4 MPa, WHSV (CH 2 ) = 2 h −1 , pure n- butane reaction performance of the catalyst changes little, but high LPG and low aromatics yields are obtained. Only under the suitable n -butane/methanol ratio, the relatively good aromatics selectivity can be obtained and maintained during the reaction process. Compared with methanol aromatization, the integrated process exhibits a much slower rate of deactivation. Addition of methanol in n -butane inhibits the dry gas production while promotes the LPG production. Water generated from methanol dehydration may occupy the catalytic active sites for olefins aromatization over the catalyst and thus suppress the production of total aromatics. In fact, water mainly suppresses benzene formation and this inhibiting effect increases with n -butane content in the feed, in contrast to its promoting effect on formation of C 8 and C 9 aromatics. Increasing methanol content in the feed, a simultaneous increase in coke content of the spent catalyst and preference for coke deposition in micropore is observed. Furthermore, the fraction of aliphatics in coke decreases, while those of less-condensed aromatics and polyaromatics incease, which is associated with the increased deactivation of catalyst.

Effect of cofeeding n-butane with methanol on aromatization performance and coke formation over a Zn loaded ZSM-5/ZSM-11 zeolite

Highly-efficient conversion of methanol to p-xylene over shape-selective Mg–Zn–Si-HZSM-5 catalyst with fine modification of pore-opening and acidic properties

Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane-type triterpenoids, (1β,2α,3β,19β)-1,2,3,19-tetrahydroxyolean-12-en-28-oic acid, (1β,3β,19β)-1,3,19-trihydroxyolean-12-en-28-oic acid, (1β,2α,3β,16β,19β)-1,2,3,16,19-pentahydroxyolean-12-en-28-oic acid, and (1β,2α,3β,19β,23)-1,2,3,19,23-pentahydroxyolean-12-en-28-oic acid, along with 16 known compounds. Their structures were established by extensive 1D- and 2D-NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep-G2 cells.

Bei‐Bei Zhang

Papers

New Cytotoxic Triterpenoids from the Aerial Parts of Euphorbia sieboldiana