|
Biomass gasification technology is the use of biomass is one of the most effective ways, while the gasification process tar byproducts great harm. It is at a low temperature (lt; 200 ℃) condensed into a liquid state, and water, carbon black and combination of fly ash, clogging pipes and equipment, reduce the overall efficiency of the device, increasing costs. Therefore, how efficient and environmentally friendly removal of tar in recent years it has become a hot research. In this paper, on the basis of previous studies with toluene biomass tar model compound, in a small catalyst evaluation device, toluene pyrolysis and catalytic cracking were studied. The main contents of this study include the following aspects: (1) In a small catalyst evaluation device, the effects of temperature on the thermal decomposition rate of toluene, carbon ratio and analyze the impact of the gas production rate and analyzed after toluene pyrolysis products the main ingredient. (2) Pyrolysis in toluene, based on the effects of calcination temperature, calcination time, reaction temperature, contact time, and S / C mass ratio of the cracking rate of the catalytic cracking of toluene, carbon ratio and analysis of gas production rate. (3) under the same conditions, influence of different components of catalysts for catalytic cracking of toluene performance. Experimental results show that: toluene occurs at high temperature thermal cracking and polycondensation reaction, the generation of the fused ring compound, carbon and flammable gases. In the thermal cracking experiment, the reaction temperature was 800 ℃, thermal cracking of toluene was 64.53%, the reaction temperature, the toluene rising thermal cracking rate, when the temperature reaches 900 ℃, toluene thermal lysis was 79.19%. This is mainly due to thermal cracking of toluene is an endothermic reaction, the temperature rises, is conducive to the reaction. On an experimental basis in the thermal cracking, catalytic cracking of toluene conducted research and found that the catalyst calcination temperature and time greatly affects the activity of the catalyst, the higher the calcination temperature, the longer the calcination time, the BET surface area decreases, the catalytic activity. By testing different calcination temperature and time of performance of the catalyst shows NiO/Al2O3, calcined at 650 ℃ for 6.0 h the NiO/Al2O3 better catalyst activity, not only improve the cleavage rate of toluene, while reducing the amount of carbon analysis, the toluene generated More light gas. Under the same conditions, the comparison of different compositions toluene cracking catalysts, catalytic effect is arranged as: Co gt; Co/La2O3 gt; NiO/CeO2/Al2O3-a gt; NiO/Al2O3 gt; NiO/CeO2/Al2O3- c gt; Ni gt; NiO/CeO2/Al2O3-b gt; Ni/La2O3 gt; Al2O3. Wherein, Co, Co/La2O3 and NiO/CeO2/Al2O3-a catalytic cracking of toluene to make a catalyst, toluene can cracking rate of 95% or more.
|