Pyrolysis and coking behavior of CxHy with different structures in microchannel continuous flow reactor

Coking with carbon deposition in hydrocarbon fuel (C x H y ) pyrolysis at high temperature is a serious problem to be considered. In this work, single component C x H y with different structures was used as the probe of the carbon deposition. Thirteen simple and representative of alkanes, cycloalkanes , aromatics and O-containing C x H y were selected as the model compounds to decompose and coking in microchannel continuous flow reactor under the same conditions. The distributions of gas, liquid and solid phase products formed by C x H y pyrolysis were characterized by GC, GC-MS, SEM and TPO-IR respectively. The results demonstrate that the molecular structure of C x H y has a great influence on pyrolysis and coking behavior. For all alkanes, CH 4 , C 2 H 4 , C 3 H 6 and C 4 H 8 are the most abundant in gaseous products, and their total content exceeds 70 %. For cycloalkanes, monocyclic cyclohexane pyrolysis tends to produce C 2 H 4 , C 4 H 8 and 1,3-C 4 H 6 , while bicyclic decahydronaphthalene pyrolysis tends to produce CH 4 , C 2 H 4 and C 3 H 6 . For aromatics, CH 4 and C 2 H 4 are the main products in the pyrolysis gas phase of benzene, toluene and ethylbenzene . Interestingly, in the liquid phase of the pyrolysis of O-containing C x H y (ethanol, acetone and tetrahydrofuran), most of the products are oxygenated compounds and no aromatics. SEM and TPO-IR revealed that at least three carbon species were formed by cracking of C x H y molecules with different structures, including amorphous, filamentous and granular carbon. However, due to the great and complex influence of C x H y molecular structure on the micro morphology of carbon deposition, it is difficult to classify all carbon species at present, which needs further experiments and researches.