HZSM-5催化剂的催化脱硫反应研究

Research of catalytic desulfurization reaction of HZSM-5 catalyst

采用浸渍法制备了一系列不同镧负载量的HZSM 5分子筛催化剂,并对其进行了X射线衍射、红外光谱、比表面和NH3-程序升温脱附等方面的表征。结果表明,HZSM 5分子筛的结晶度均达到了85%以上,掺镧后的HZSM 5分子筛在波数1100cm-1附近的非对称振动特征峰有一定程度的蓝移,BET法的比表面积及直径、单点体积、BJH法的吸附体积及脱附体积均有所增大,反应的比表面活性有所提高,致使弱酸量大幅度减少,中强酸、强酸量大幅度增大。在活性氢物质甲醇存在时,固定床微型反应器中噻吩的催化转化反应结果表明,催化剂的脱硫反应活性明显增强,噻吩转化率提高,噻吩转化为H2S的量增加,但液相产物趋向复杂,选择性有所降低,且在掺镧约1 0%左右噻吩的转化率达到51.3%。

The state of La over HZSM-5 zeolite and properties of zeolite were studied by X-ray diffraction(XRD), infrared spectrometer(IR), NH_3-temperature program desorption and BET methods. There are more than 85% relative crystallinities for the La-modified HZSM-5 zeolites catalysts applied in the test. There is little blue shift for wave number on IR spectrum, with no influence in the whole framework structure, certain increase in BET specific surface area, pore volume, BET pore diameter and BJH adsorption and desorption volume while HZSM-5 zeolites were modified by rare earth metal La. The experimental results show that impregnating method could make La^(3+) ion enter into the framework of the HZSM-5 zeolite, which results in the proportion of the weak acid to decrease, and the proportion of the mid-strong acid or strong acid to increase. The cracking deslfurization reaction of thiophene over HZSM-5 or La-modified HZSM-5 molecular sieve catalyst in the presence of activated hydrogen substance was investigated in the micro fixed-bed catalytic reactor. The results show that compared to parent HZSM-5 molecular sieve, La-modified HZSM-5 leads to higher thiophenic conversion and hydrogen sulfide yield, while more byproducts are formed. There is a maximum of thiophenic conversion of 51.3% and hydrogen sulfide of 18.1% while the La content is modified by 1.0% in the HZSM-5 zeolite.