Focused on a new process of integrated coal pyrolysis with carbon dioxide reforming of ethane(CP-CRE)over different catalysts.This work is to find an optimum catalyst for CRE to improve coal tar yield of CP-CRE,and compare CP-CRE with those under atmospheres of nitrogen and carbon dioxide reforming of methane(CRM).The main results are summarized as follows:(1)The different catalysts were prepared by impregnation method.Under the condition of C/C molar ratio is 1,integrated process of coal pyrolysis with carbon dioxide reforming of ethane was carried out at 650 oC.Through the experiments,it is found that the Ni/MgO catalyst is suitable for this integrated process.It is good at adsorpting CO2 on account of the alkalinity of MgO,and Ni O has a good dispersion on MgO which won’t make the ethane excessive cracked to produce carbon deposition and can improve coal tar yield effectively.Meanwhile,it is found that catalyst support has a greater influence on tar yield and tar composition than different active components.The dispersion of NiO on the Ni/Al2O3 catalyst could be improved by addition of MgO promoter,and the MgO-Ni/Al2O3 showed better resistance of carbon deposition and better catalytic activity and stability in CP-CRE.(2)The pyrolysis experiments were carried out in a fixed-bed reactor under gas atmospheres of N2,CRM and CRE by Ni/MgO respectively.It was found that the NMH coal tar yield increased first and then decreased with the increase of temperature,and reached the highest at 650 oC.Both CP-CRE and CP-CRM are conductive to promote the tar yield,and the tar yield of CP-CRE and CP-CRM at 650 oC is 1.26 and 1.19 times as that in coal pyrolysis under N2 atmosphere,respectively.The water yield of integrated process increased with the increase of temperature,and the yield of char decreased with the increase of temperature.(3)The simulated distillation analysis of coal tar indicated that light oil content in tar from CP-CRE and CP-CRM is higher than that from coal pyrolysis under N2,and light oil content in tar increased with the increase of temperature.The properties of tar were characterized by gas chromatography-mass spectrometry(GC/MS)and nuclear magnetic resonance(NMR).It is found that the integrated process promote the hydrogenation of tar,and the integrated process could inhibit the formation of the condensed aromatic rings relative to the CP-N2process so the integrated process could produce more products like benzene,phenol and naphthalene.The results mean that some active species from CRE participate in stabilizing coal cracking fragments and inhibiting secondary reaction,and consequently there is more uncondensed aromatic rings in the tar from integrated process and the amount of aromatic protons increased. |