NiMo/HBETA as Catalysts with Dual Functions Beneficial to Waste Tyre Pyrolysis

Abstract

The world is running out of petroleum with the increasing demand in the fuel consumption. Oil from waste tyres is one of interesting fuels to be developed, and pyrolysis is one of the suitable processes to utilize these waste tyres. In the pyrolytic oil from waste tyres, sulphur compounds are largely present in the form of polar-aromatics such as thiophene, benzothiophene, and dibenzothiophene, which can cause poisoning of the active sites on the catalyst. Moreover, if sulphur-containing oils are used as fuels, SO2 that is a pollutant can be produced during combustion. In our previous work, Ni/HBETA was proven to be a potential waste tyre pyrolysis catalyst; thus, since NiMo is one of good desulphurization catalyst, it was also expected to have both pyrolysis and sulphur removal activities beneficial to waste tyre pyrolysis. The purposes of this work were to study the cracking ability as well as the desulphurization ability of NiMo loaded on HBETA catalyst for tyre pyrolysis, and to study the change of sulphur compounds when the compositions of the bimetallic catalysts are varied. The results showed that 5%Ni with 20%Mo catalyst had both good cracking and desulphurization abilities. The pyrolytic oil obtained from the catalyst had lower polar-aromatic and sulphur contents than those from the other catalysts. It was mainly composed of full- range naphtha which had large amounts of saturated hydrocarbons and mono-aromatics. Moreover, the sulphur compounds in the pyrolytic oils were analyzed by GC-MS (TOF). It was found that sulphur compounds were mainly in the kerosene range (C10–C13) such as benzo[b]thiophene, 2,7–dimethyl, benzo[b]thiophene, 2–ethyl–7–methyl- and dibenzothiophene.