摘要
采用固定床反应器,以甲醇为原料,在反应温度为430℃和反应空速为2 h-1的条件下,考察了不同硅铝比HZSM-5分子筛催化剂的甲醇制芳烃反应(MTA)性能,并采用X射线衍射(XRD)、氨气程序升温脱附(NH3-TPD)、物理吸附、傅立叶红外光谱(FT-IR)等技术对催化剂进行了表征。结果表明:MTA反应是强酸主导的催化反应,随着分子筛硅铝比的降低,分子筛总酸量逐渐增加,强酸相对总量逐渐提高,其中弱酸相对总量降低。这主要是由于分子筛中Al含量逐渐上升,作为强酸位的Si-OH-Al逐渐增加所致,催化剂反应活性与之呈正向相关的关系。当HZSM-5催化剂中的强弱酸总量比由0.3增加到0.6时,苯-甲苯-二甲苯(BTX)的选择性由36%增至64%,说明催化剂的活性显著提高;当强弱酸总量比由1.1增至1.5时,BTX选择性变化仅为0.92%,催化性能提升不明显,HZSM-5分子筛的MTA反应性能与其硅铝比呈反向相关关系。
Evaluation of methanol-to-aromatics （MTA） reaction on HZSM-5 zeolite catalyst with different silica to alumina ratio was performed in a fixed bed reactor at reaction temperature of 430 ℃ and GHSVof 2 h-1. The catalyst was characterized by X-ray diffraction （XRD）, ammonia temperature-programmed desorption （NH3-TPD）, BET specific surface area determination, and Fourier transform infrared spectrometry （FT-IR）. The results showed that the MTA was a strong acid catalytic reaction. With the decrease of silica to alumina ratio, the total amount of acid in the catalyst increased in the form of elevated strong acid level and low weak acid level. This was mainly due to the fact that an elevated A1 content enhanced the Si-OH-A1 linkage （strong acid, denoted as S）, meanwhile it reduced the Si-OH linkage （weak acid, denoted as W）, resulting in better catalytic activity. When S to W ratio increased from 0.3 to 0.6, the selectivity of benzene to toluene and xylene （BTX） increased from 36% to 64%. While S to W ratio increased from 1.1 to 1.5, the BTX increased only 0.92%. In all, the catalytic activity of HZSM-5 zeolite in MTA reaction was in an inverse relationship with silica to alumina ratio.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2013年第2期147-151,共5页
Chemical Reaction Engineering and Technology
基金
国家重大基础研究计划(973)项目(2009CB623504)
关键词
硅铝比
HZSM-5分子筛
甲醇制芳烃
ratio of silica to alumina
HZSM-5 molecular sieve
methanol-to-aromatics reaction
