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Oxidative Catalytic Cracking and Reforming of Coal Pyrolysis Volatiles over NiO
journal contribution
posted on 2020-05-26, 17:04 authored by Dechao Wang, Lijun Jin, Baoyong Wei, Jiannan Lv, Yang Li, Haoquan HuCatalytic cracking of Pingshuo (PS)
coal pyrolysis volatiles was
investigated over NiO on a two-stage fixed bed reactor. The effect
of the NiO loading amount and catalytic upgrading temperature on the
products distribution was investigated, and the role of NiO during
the catalytic upgrading was discussed through several characterizations.
It is shown that the partial reduced NiO to Ni during catalytic cracking
results in oxidative catalytic cracking and reforming of coal pyrolysis
volatiles. The tar yield decreases from 14.2 wt % without using NiO
to 3.6 wt % with 9.0 g NiO loading at a cracking temperature of 550
°C, corresponding to the tar conversion being 74.6 wt %. With
the increase of the cracking temperature, the tar yield decreases
first and then increases, and the lowest tar yield is 5.2 wt % at
550 °C over 6 g NiO loading. After catalytic cracking of coal
pyrolysis volatiles, the used NiO is fully reduced to Ni, and the
catalytic performance of used NiO was evaluated three times. The results
indicate that the NiO-2nd (used NiO) shows high tar reforming performance
in terms of the decrease of tar (10.7 wt %) and water yield (4.8 wt
%), and H2 yield increases significantly to 104 mL/g coaldaf at 550 °C compared to those without using NiO. However,
the catalytic performance of used NiO decreases gradually with increase
of cycle times; the tar and water yield increase to 13.3 and 7.4 wt
%, respectively, and H2 yield decreases to 31 mL/g coaldaf over NiO-4th. The gradual decrease of catalytic performance
of used NiO is due to the deposition of carbon and formation of Ni2S3.