超临界状态下正十二烷/异辛烷双元模型燃料的催化裂解反应

在超临界状态下,以HZSM-5分子筛为催化剂,在固定床反应器中进行了正十二烷与异辛烷质量比为1∶1的正十二烷/异辛烷双元模型燃料催化裂解反应的研究,考察了转化率、气体产物收率、主要气体产物选择性及积碳量与裂解温度和压力的关系。实验结果表明,在超临界状态下,双元模型燃料的转化率和气体产物收率随裂解温度的升高而增加,裂解温度为400～450℃时,气体产物的主要组分为丙烷、异丁烷和正丁烷,与纯正十二烷裂解的气体产物分布类似;裂解温度为450～500℃时,甲烷、乙烷和氢气的选择性明显提高,气体产物分布与纯异辛烷裂解的气体产物分布相近。在0.1～7.0MPa的范围内,随裂解压力的增大,在双元模型燃料中正十二烷转化率和气体产物收率下降。积碳量随裂解温度的升高呈现先降低后增加的趋势,450℃时积碳量最少。

Catalytic Cracking of n-Dodecane/Isooctane Binary Model Fuel Under Supercritical Conditions

Catalytic cracking of the n-dodecane/isooctane binary model fuel over HZSM-5 zeolite catalyst was carried out under supercritical conditions in a fixed-bed reactor.The mass ratio of n-dodecane to isooctane in binary model fuel was 1 ∶ 1.Influences of cracking temperature and pressure on conversion of the fuel,yields to gas products,selectivities to main gas products and carbon deposit on catalyst were investigated.Under supercritical conditions the conversion and gas product yield increased with rising of cracking temperature.The major gas products were propane,isobutane and n-butane in temperature range of 400-450 ℃,which were similar to that of pure n-dodecane catalytic cracking.In temperature range of 450-500 ℃,selectivities to methane,ethane and hydrogen increased significantly,which were close to that of pure isooctane catalytic cracking.In the pressure range of 0.1-7.0 MPa,both n-dodecane conversion and gas products yields decreased inversely with cracking pressure.Amount of carbon deposit on catalyst dropped first and then increased with increasing of cracking temperature,and the minimum appeared at 450 ℃.