Formation Of Formate In The Side-chain Alkylation Of Toluene With Methanol

This thesis focused on the side-chain alkylation of toluene with methanol on faujasite zeolites and the preparation of biomorphic solid base with hierarchical pores. In the first part, KX and NaY zeolites were modified mainly with K2CO3, and the catalytic performances in side-chain alkylation were compared in terms of their surface properties. The formation and function of formate in the reaction were well discussed. In the second part, biomorphic super base CaO were prepared via an exotemplating pathway using degreasing cotton and vegetable sponge as templates and calcium acetate as CaO precursors, and were characterized by X-ray diffraction, adsorption of nitrogen, scanning electron microscopy and so on. The influence of steam and evacuation treatments on the surface property was investigated.The main progresses of this thesis are:1) Loading alkali carbonates can improve the catalytic activity of KX zeolite at low temperature effectively. However, due to the strong basicity of the catalysts, methanol molecules were almost completely decomposed into CO and H2, which resulted in the hydrogenation of styrene. Hence ethylbenzene was the main product on K2CO3/KX.2) During the side-chain alkylation process, various amounts of formate were formed on the surfaces of modified KX and NaY zeolites. These formate species derived from the reaction of carbonates with formaldehyde, the dehydrogenation product of methanol. The formation of formate was closely related to the basicity of the catalysts and the reaction temperature. A lot of formate molecules can be formed on K2CO3/KX at573～673K.3) The surface acid/base property of the catalysts was modified by the formed formate species, and thus generated more effective active sites, which promoted the formation of side-chain alkylation products.4) Biomorphic CaO can be prepared using degreasing cotton and vegetable sponge as exotemplates. The surface area of these solid bases had dramatic change with the storage time and calcination condition used. Through steam treatment followed by evacuation, the surface area of these solid bases can be greatly improved. A novel kind of microporous-mesoporous-macroporous material can be generated via this route and it exhibited better catalytic performance.