废ZSM-5分子筛再晶化并应用于甲烷部分氧化性能研究

Study on recrystallization of waste ZSM-5 molecular sieve and its application in partial oxidation of methane

废ZSM-5分子筛资源化利用可有效减少工业固废排放、降低环境污染,是一条节约能源、绿色环保且可持续发展的路线。探究了沸石废分子筛催化剂(主要为废ZSM-5分子筛)定向再生为ZSM-5分子筛的绿色回收工艺,重点考察了模板剂用量、补加硅源用量和模板剂种类对沸石废分子筛催化剂回收率的影响。通过X射线衍射(XRD)、氮气吸/脱附和扫描电镜(SEM)等分析合成分子筛的结晶度、比表面积和形貌,从而得出最佳合成条件:模板剂为四丙基氢氧化铵(TPAOH)、硅源与模板剂比例为n(SiO_(2)):n(TPAOH)=1:1且补加硅源量与废分子筛硅源量比例为n(Si补加):n(Si废)=2.5:1.0,对应废分子筛催化剂回收率可达88.0%。利用废分子筛催化剂再晶化所得ZSM-5分子筛作为载体制得的催化剂用于甲烷部分氧化反应进行性能测试,在600°C下较未变废原料表现出更优异的CH4转化率、CO选择性和H2选择性。

The resource utilization of waste ZSM-5 molecular sieve can effectively reduce the discharge of industrial solid waste and reduce environmental pollution,which is an energy saving,green and sustainable development route.The green recovery process of directional regeneration of waste zeolite molecular sieve catalyst(mainly waste ZSM-5 molecular sieve)into ZSM-5 molecular sieve was explored,focusing on the impact of template dosage,external silicon source dosage and template type on the recovery rate of waste zeolite molecular sieve catalyst.X-ray diffraction(XRD),nitrogen adsorption/desorption,and scanning electron microscopy(SEM)were used to analyze crystallinity,specific surface area,and morphology of the synthesized molecular sieve.The optimal synthesis conditions are optimized as follows:when the template is tetra propyl ammonium hydroxide(TAPAOH),the ratio of silicon source to template agent is n(SiO_(2)):n(TPAOH)=1:1,and the ratio of the amount of silicon added to the amount of silicon source of waste molecular sieve is n(Si addition):n(Si waste)=2.5:1.0,the recovery rate of waste zeolite molecular sieve catalyst can reach 88.0%.The ZSM-5 molecular sieve catalyst,which is recrystallized using waste molecular sieve catalyst,is used as a carrier for catalytic performance testing in methane partial oxidation reaction.It exhibits better CH4 conversion rate,CO selectivity,and H2 selectivity against unchanged waste raw materials at 600°C.