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HZSM-5ゼオライト触媒によるトルエンのメチル化反応の形状選択性の解析 : 結晶内および外表面の寄与

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Title: HZSM-5ゼオライト触媒によるトルエンのメチル化反応の形状選択性の解析 : 結晶内および外表面の寄与
Other Titles: Analysis of shape selectivity of methylation in toluene over HZSM-5 zeolites : Contribution of outer and inner surfaces of the crystallite
Authors: 橋本, 健治1 Browse this author
増田, 隆夫2 Browse this author →KAKEN DB
播口, 陽一3 Browse this author
Authors(alt): Hashimoto, Kenji1
Masuda, Takao2
Hariguchi, Youichi3
Keywords: HZSM-5 Zeolites
Issue Date: 1989
Publisher: 日本化学会
Journal Title: 日本化学会誌
Volume: 1989
Issue: 3
Start Page: 575
End Page: 582
Publisher DOI: 10.1246/nikkashi.1989.575
Abstract: A model is developed which describes the activity and shape selectivity for the methylation of toluene to produce xylene isomers over HZSM-5 zeolite catalysts by taking account of both intracrystalline diffusion and acid strength distributions inside and outside crystallite. Effective intracrystalline diffusivities were directly measured by use of high-silica HZSM-5 zeolite which had no catalytic activity for the methylation of toluene in a high temperature range (473 - 673 K). The ratio among the diffusivities of p-, m- and o-xylene was about 10:1:1 in the above temperature range. The acid sites inside and outside the crystallite were discriminated from each other, and each acid strength distribution function was measured by combining the two methods developed by ourselves. Rate constants of methylation and isomerizations of xylenes inside and outside the crystallite were estimated by performing these reactions over two kinds of catalysts : one has acid sites only inside the crysatllite, the other only outside the crystallite. Using these values, the proposed model was found to predict satisfactorily the apparent shape selectivity. A chart (Fig. 11) based on the proposed model is also presented which gives a guide in preparing highly selective HZSM-5 catalysts for the methylation of toluene.
HZSM-5類似ゼオライト触媒を用いたトルエンのメチルイ化反応の形状選択牲を表現するモデルを提出した。このモデルでは結晶内拡散と結晶の内・外表面の酸強度分布曲線の形状選択性への影響を考慮している。反応温度での結晶内の有効拡散係数はトルエンのメチル化反応の温度範囲 (473~673K) で活性をもたない高シリカの HZSM-5 を用いて直接測定した。p-, m- および o-キシレンの拡散係数の比はおよそ 10:1=1 であった。結晶内と結晶外表面の酸強度分布曲線を著者らがすでに提出した方法により分離測定した。結晶内部と結晶外表面でのトルエンのメチル化反応とキシレンの異性化反応の速度定数は2種類の触媒を用いて推定した。一つは結晶内部のみに酸点をもつ触媒, 他は結晶外表面にのみ酸点をもつ触媒である。これらの特性値を用いてモデルを検討した結果, モデル式は見かけの形状選択性をよく予測することがわかった。さらに,本解析法を用いることで, トルエンのメチル化反応に対して高い形状選択性をもつ HZSM-5 ゼオライトを調製するための指針を与える線図を得た。
Rights: ©1989 The Chemical Society of Japan
Type: article
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 増田 隆夫

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