Synthesis And Adsorption Properties Of SAPO-35 Molecular Sieve

SAPO-35 molecular sieve belongs to silicoaluminophosphate molecular sieve.Its skeleton is negatively charged and has cation exchange performance.Mainly used in the field of refining and petrochemicals.SAPO-35 belongs to the LEV configuration microporous molecular sieve.The pore size is between 0.36 nm and 0.48 nm.It consists of a four-membered ring,a six-membered ring and an eight-membered ring.SAPO-35 molecular sieve has a uniform pore structure,high specific surface area,hydrothermal stability and surface polarity,making SAPO-35 molecular sieve an excellent catalyst and carrier.The SAPO-35 molecular sieve structure has uniform small internal pores and exhibits selective catalytic properties in the catalytic reaction.The main work of this paper is as follows:1.SAPO-35 molecular sieve was synthesized by using MDEA as a single template.The average particle size was about 5μm,and the pore size was roughly distributed between 0.6nm and 0.8nm.When the ratio of silicon to aluminum is 0.4 and 0.7,the phase of SAPO-34 will be formed first when the crystallization temperature is 190℃or 200℃.The phase of SAPO-34 can be converted into SAPO-35 phase by increasing the crystallization temperature to 210℃.Therefore,when the ratio of silicon to aluminum is 0.4 or 0.7,210℃is the crystallization temperature suitable for the synthesis of SAPO-35 molecular sieve;when the ratio of silicon to aluminum is 1.0,when the crystallization time is 24 h,the phase ofSAPO-34 is formed first,and the crystal is extended.The phase of SAPO-34 can be converted to the SAPO-35 phase by a time of 36 h.Therefore,when the ratio of silicon to aluminum is 1.0,36 h is suitable for the crystallization time of SAPO-35 molecular sieve synthesis;when the ratio of silicon to aluminum is 1.0,the crystal morphology of the sample is more regular with the crystallization time prolonging,gradually becoming square,crystallizing It tends to be good.2.For the first time,SAPO-35 molecular sieve was synthesized by MDEA/HMI as double template.The average particle size was about 6μm,and the pore size was roughly distributed between 0.6nm and 0.8nm.When the ratio of phosphorus to aluminum is 1.2 and the crystallization temperature is 200℃,the phase of SAPO-5 will appear first when the crystallization time is 24 h.When the crystallization time is extended to 36 h,the phase of SAPO-5 will be converted into the phase of SAPO-35.,indicating that the ratio of phosphorus to aluminum is 1.2,the crystallization temperature is 200℃,36 h is the crystallization time suitable for SAPO-35 molecular sieve synthesis;the ratio of phosphorus to aluminum is 1.4,the crystallization time is 36 h,and crystallization at 190℃ The intermediate phase of SAPO-34 is formed first,and the crystallization temperature can be converted to the phase of SAPO-35 by increasing the crystallization temperature to 200℃ or 210℃ When the ratio of phosphorus to aluminum is 1.4 and the crystallization time is 36 h,the efficiency and energy consumption are comprehensively considered.200℃ is suitable for the crystallization temperature of SAPO-35 synthesis;SAPO-35 prepared with MDEA as a single templating agent will have large particles of SAPO-34,while MDEA/HMI is a double templating agent for pure sample.The phase of the SAPO-35 molecular sieve has a uniform particle size and a regular square structure.