CAJ | 학술논문

采用连续流动装置对正癸烷和二甲苯在超临界压力下的热裂解对比研究.用气相色谱和色质联用仪对其气相产物和液相产物进行分析,计算气相产物产率和裂解转化率,并运用计算化学方法获得正癸烷和二甲苯不同化学键的键能,从实验和理论上分析其裂解反应的难易程度和裂解规律.实验结果表明,在4 MPa和650、700、750°C条件下,正癸烷比二甲苯更容易裂解,正癸烷裂解产物以C1-C3小分子的烃类和氢气为主,而二甲苯裂解产物主要为乙苯、甲苯和其它芳香类化合物;键能计算结果表明,正癸烷碳链骨架的C-C键能和C-H键能均较小,裂解反应的诱发步骤应该是C-C键断裂,而二甲苯苯环上C-C和C-H键能均较大,裂解诱发步骤应该是侧链甲基脱氢反应.因此正癸烷裂解反应以C-C键断裂和脱氢反应为主,二甲苯裂解主要发生侧链甲基C-C键断裂和脱氢反应,而芳环则比较稳定,理论计算键能分析与裂解实验结果一致.
채용련속류동장치대정계완화이갑분재초림계압력하적열렬해대비연구.용기상색보화색질련용의대기기상산물화액상산물진행분석,계산기상산물산솔화렬해전화솔,병운용계산화학방법획득정계완화이갑분불동화학건적건능,종실험화이론상분석기렬해반응적난역정도화렬해규률.실험결과표명,재4 MPa화650、700、750°C조건하,정계완비이갑분경용역렬해,정계완렬해산물이C1-C3소분자적경류화경기위주,이이갑분렬해산물주요위을분、갑분화기타방향류화합물;건능계산결과표명,정계완탄련골가적C-C건능화C-H건능균교소,렬해반응적유발보취응해시C-C건단렬,이이갑분분배상C-C화C-H건능균교대,렬해유발보취응해시측련갑기탈경반응.인차정계완렬해반응이C-C건단렬화탈경반응위주,이갑분렬해주요발생측련갑기C-C건단렬화탈경반응,이방배칙비교은정,이론계산건능분석여렬해실험결과일치.
@@@@The pyrolysis of n-decane and dimethylbenzene under supercritical pressure was studied using a continuous flow reactor. Samples were heated to a temperature of 650, 700, or 750 °C under a pressure of 4 MPa without oxygen. n-Decane pyrolyzed more easily than dimethylbenzene. We analyzed gaseous products by online gas chromatography, and liquid products by gas chromatography-mass spectrometry, al owing us to calculate the cracking gas yield and cracking conversion of these systems. A quantum chemistry computation was used to evaluate the binding energies of C-C and C-H bonds in n-decane and dimethylbenzene. Both experimental and theoretical results were also used to analyze the cracking reactivity of these species. Analysis of the components in the products indicated that the main products of n-decane were C1-C3 hydrocarbons and hydrogen, whereas ethylbenzene, toluene and other aromatic compounds were the main products of dimethylbezene after pyrolysis. Binding energy calculations showed that both C-C and C-H bonds in n-decane possessed lower binding energies than those in dimethylbezene, and a C-C bond was the weakest. In dimethylbenzene, a C-H bond in the methyl groups was the weakest, and its binding energy was much smal er than those of the C-C and C-H bonds in the benzene ring. Therefore, the main reactions in the cracking process of n-decane are breakage of a C-C bond and dehydrogenation. However, the cracking process in dimethylbenzene mainly involves the fracture and dehydrogenation of methyl groups. The theoretical calculations reasonably explained the experimental phenomena.