钾改性Beta分子筛Brönsted酸性能对十氢萘加氢异构化及加氢裂化反应的影响  

Effect of Various Brönsted Acidity of the Beta Zeolite Modified by K^(+) on Hydro-isomerization and Hydrocracking of Decalin

作　　者：焦凡凡 毛以朝[1] 龙湘云[1] 王永睿[1] 刘诗哲 JIAO Fanfan;MAO Yichao;LONG Xiangyun;WANG Yongrui;LIU Shizhe(Research Institute of Petroleum Processing, SINOPEC, Beijing 100083, China)

机构地区：[1]中国石化石油化工科学研究院,北京100083

出　　处：《石油学报（石油加工）》2022年第4期760-770,共11页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：中国石油化工股份有限公司合同项目(S119037)基金资助。

摘　　要：为了提高十氢萘加氢转化生成桥环异构体的选择性,采用钾(K^(+))后浸渍法对Beta分子筛进行了酸性调节;采用X-射线衍射(XRD)、扫描电子显微镜(SEM)、N_(2)吸附-脱附(BET)、红外光谱(Py-IR)等分析手段对改性前后的分子筛进行了表征。采用孔饱和浸渍法制备了Pt/Beta-Al_(2)O_(3)催化剂,在氢气压力4.0 MPa、温度240~300℃、氢/油摩尔比12.62、质量空速10.56 h^(-1)的条件下,以十氢萘为模型化合物进行了加氢异构化和加氢裂化反应研究。结果表明:随着K_(2)O负载质量分数从0.105%增加到0.403%,改性前后分子筛的结构及孔道性质未发生明显变化,分子筛Brönsted(B)酸酸量从209μmol/g逐渐下降到123.9μmol/g;十氢萘加氢转化过程遵循异构化-开环-裂化连串反应机理,随着反应温度升高,异构选择性降低,开环和裂化反应选择性升高,总转化率增大;反应温度低于280℃时,桥环异构产物选择性可以达到90%以上。在反应温度300℃的条件下,随着K^(+)改性分子筛的B酸酸量降低,产物异构选择性增加,开环选择性和裂化反应选择性降低。K^(+)通过抑制裂化反应可以明显提高桥环产物的选择性。To improve the selectivity of decalin converting into bridge ring isomers by hydrogenation,the acidity of zeolite Beta was adjusted using K^(+) post-impregnation method.X-ray diffraction(XRD),scanning electron microscopy(SEM),N_(2) adsorption-desorption(BET),and pyridine adsorption Fourier-transform infrared(Py-IR)were used to characterize zeolites before and after modification.Pt/Beta-Al_(2)O_(3) catalysts were prepared by pore saturation impregnation method.Using decalin as the model compound,the study of hydroisomerization and cracking reaction was performed under the hydrogen pressure of 4.0 MPa,the temperature of 240—300℃,the hydrogen to oil molar ratio of 12.62,and the mass space velocity of 10.56 h^(-1).The results show that the structure and pore properties of zeolites before and after modification have not changed significantly with the load mass fraction of K_(2)O increasing from 0.105%to 0.403%,but the amount of Brönsted acid of zeolites is gradually decreased from 209μmol/g to 123.9μmol/g.The procedure of decalin hydrogenation conversion is in accordance with the chain reaction mechanism of isomerization-ringopening-cracking.With the increasing of reaction temperature,the selectivity of isomerization is decreased,but that of the ring opening and cracking reaction is increased,and the total conversion is increased.The selectivity of bridge-ring isomers can reach more than 90%when the reaction temperature is below 280℃.With the decreasing of Brönsted acid content of K^(+)modified zeolites,the selectivity of product isomerization is increased,and that of ring opening and cracking reaction is decreased when the reaction temperature is at 300℃.K^(+)can significantly improve the selectivity of bridged ring products by inhibiting cracking reaction.

关 键 词：Beta分子筛 Brönsted酸 十氢萘 加氢异构化 桥环异构体 

分 类 号：TE624[石油与天然气工程—油气加工工程] TQ426.95[化学工程]