Synthesis And Adsorption Properties Of ZSM--35 Molecular Sieve

In recent years,as people gradually began to pay attention to FER topology molecular sieve,ZSM-35 molecular sieve also attracted people’s attention.ZSM-35 molecular sieve is a kind of synthetic high-silicon zeolite molecular sieve with FER topology,with suitable pore size,adjustable acidity,good hydrothermal stability,shape-selective catalytic ability and anti-carbon deposition abilityThe main work of this paper is as follows:Isobutylene can be used to produce methyl tert-butyl ether(MTBE),and the demand for MTBE as a gasoline additive has been increasing.Most of MTBE is synthesized from methanol and isobutene as raw materials,with the aid of acidic catalysts,so that the demand for isobutene has also increased dramatically.When the ferrierite represented by ZSM-35 molecular sieve is used as a catalyst,the unique pore structure and the distribution of acid sites of ferrierite are favorable for the isomerization reaction.And the yield of isobutene is higher.This article uses hydrothermal synthesis to synthesize ZSM-35 molecular sieve,and systematically explores the synthesis conditions and different influencing factors of ZSM-35 synthesis.In this paper,three different template agents were used,namely pyrrolidine,cyclohexylamine,and ethylenediamine to explore the effect of different synthesis conditions on the synthesis of ZSM-35 molecular sieve.1.ZSM-35 molecular sieve was synthesized with pyrrolidine as a single template agent,and30% silica sol was selected as the silicon source,sodium metaaluminate was all the aluminum source and part of the alkali source.The effects of the amount of water,the amount of potassium hydroxide,different crystallization times and the amount of pyrrolidine on the ZSM-35 molecular sieve were studied.The ratio of silicon to aluminum is 20,the molar ratio of template to alumina is 15,the crystallization temperature is 190℃,and the crystallization time is 12-54 h.From the measured XRD,the product obtained when the crystallization time is 48 h is pure phase ZSM-35 molecular sieve.The silicon-aluminum ratio is 20,the molar ratio of the template agent to alumina is 3-20,the crystallization temperature is 190°C,and the time is 48 h.The molar ratio of the template agent to alumina is 7-20 by XRD,and the resulting product is pure Phase ZSM-35 molecular sieve.The raw material silicon-aluminum ratio is 20,the template agent to alumina molar ratio is 10,the deionized water to alumina molar ratio is 800-1800,the crystallization temperature is 190°C,and the crystallization time is 48 h.The molar ratio ofdeionized water to alumina is 1200-1600,the product is pure phase ZSM-35 molecular sieve2.Synthesize ZSM-35 molecular sieve with cyclohexylamine as a single template agent,and select 30% silica sol as the silicon source,sodium metaaluminate as the entire aluminum source and part of the alkali source.Under the conditions of static hydrothermal crystallization Molecular sieve.The effects of silicon-aluminum ratio and temperature on ZSM-35 molecular sieve were studied.The crystallization temperature is 190℃,the crystallization time is 48 h,the raw material silicon-aluminum ratio is 18/20/22/24/30,and the product obtained is pure phase ZSM-35 molecular sieve.The ratio of silicon to aluminum is 18/20,and the diffraction peak of mordenite appears at 2θ=27.7°.The crystallization temperature was adjusted to 200°C.The XRD pattern of the silicon-aluminum ratio of 22/24/30 showed a small peak belonging to the quartz phase at 2θ=21.7°,and the silicon-aluminum ratio was 18.The XRD pattern of the two days of crystallization was 2θ= The diffraction peak of mordenite appeared at 27.1°.When the ratio of silicon to aluminum is 20,the prepared product is pure phase ZSM-35 molecular sieve.Adjusting the crystallization temperature to 220°C and the silicon-aluminum ratio to 18-30.The XRD pattern shows a small peak belonging to the quartz phase at 2θ=21.7°,and a diffraction peak of mordenite at 2θ=27.7°.When the ratio of silicon to aluminum is 18/20/24/30,the diffraction peak of the quartz phase appears at 2θ=9.8°.Compared with the temperature at 200℃,it is found that the higher the temperature,the easier the 2θ=21.7° belongs to the small peak of the quartz phase.It appears that the appropriate lowering of the temperature can eliminate the small peaks belonging to the quartz phase,and with the further increase of the silicon-to-aluminum ratio,more and more phases belonging to the mordenite are found,indicating that an excessively high silicon-to-aluminum ratio and excessive temperature are not suitable for ZSM-35 Pure phase generation.3.ZSM-35 molecular sieve was synthesized with ethylenediamine as a single template agent,and the effect of using different silicon and aluminum sources on the synthesis of ZSM-35 molecular sieve under the same reaction conditions was studied.It is found that the use of white carbon black as the silicon source and aluminum sulfate as the aluminum source are not conducive to the formation of ZSM-35 pure phase.