Study on lightening of coal tar with metal oxide supported γ-AlO catalyst.

In this experiment, a fixed bed of pyrolysis was used to conduct pyrolysis with coal and a mixture of coal and catalyst, and the distribution and composition of tar products were studied. The pyrolysis of raw coal was carried out at different temperatures and at different constant temperature times, and the effects of pyrolysis temperature and constant temperature pyrolysis time on tar product formation from raw coal pyrolysis were studied. γ-AlO was used as the carrier, and 4 kinds of alkaline earth metal oxides (MgO, CaO, SrO, BaO), 3 kinds of subgroup metal oxides (FeO, CoO, NiO) and 5 kinds of VIII metal oxides (CrO, MnO, CuO, ZnO, MnO) were selected as active components. The supported γ-AlO catalyst was prepared by the method of equal volume impregnation and roasting in a muffle furnace. The γ-AlO catalyst was characterized by means of XPS, BET and SEM, and the mechanism of the mixed pyrolysis of coal with different metal oxide supported catalysts to generate tar was studied. The results showed that: (1) under the conditions of 450 °C, 500 °C, 550 °C and 600 °C, the maximum tar yield was 0.32 g at 600 °C, and the tar yield was higher at constant temperature for 15 min than at final temperature of 600 °C, with an increase of 15.63%. (2) FeO/γ-AlO catalyst resulted in the highest tar yield of 0.75 g, which was 134.38% higher than that of coal pyrolysis. (3) From the increase of light oil and phenol oil and the decrease of anthracene oil and asphalt, CoO/γ-AlO, FeO/γ-AlO and CrO/γ-AlO can improve the tar quality better.