Study On Catalytic Activation And Poly-generation Of Shenfu Semi-coke

Facing the dual pressures of energy resources and the environment, people are looking for effective ways to solve the problems. Multi-generation technology are concerned as a resource, energy, environment integrated technology. China is a country which is short of petroleum and gas, but relatively abundant coal resources. Semi-coke as a product of coal pyrolysis, and it is becoming increasingly important for rational utilization. This paper discussed the catalysis of metal oxide catalysts on steam gasification of shenfu semi-coke and analysed the influence law of the gasification process to activated carbon and high yield of hydrogen.Fe, Ni, Ca, Mn and Co catalyst which prepared with coprecipitation, mechanical grinding method and microbeads carrier, activated aluminium oxide carrier were used to study the effect of activation temperature, activation time, steam flow, catalyst composition, dosage and adding methods etc. On the propert ies of activated carbon and the gas composition which obtained from steam gasification of shenfu semi-coke in fixed bed tubular reactor. The adsorption of activated carbon was characterized by iodine adsorption and methylene blue adsorption. The morphology and pore structure of activated carbon were studied by SEM, XRD and nitrogen adsorption.The influence of different catalysts on steam activation of the semi-coke were different. The order of catalytic activity: CaO> Fe₂O₃>NiO>CoO₂≈MnO₂. CaO made the iodine value increased and the methylene blue adsorption value decreased. The iodine value, methylene blue adsorption value can be increase with adding Fe₂O₃ and NiO. CoO₂ and MnO₂ have little effect on the iodine value and methylene blue adsorption value. CaO, Fe₂O₃ and NiO had catalysis for generating H₂, and the yield of H₂ increased to 74.27%, 71.90% and 70.27% from primary 67.28%, respectively. CoO₂ had negative catalysis for generating H₂. The yield gas. of H₂ decreased to 66.20% from 67.28%. MnO₂ had little influence on generating H₂. Meanwhile, CaO,NiO,Fe₂O₃ can decrease the yield of activated carbon and increase the total yield of activatedBy comprehensive consideration of the performance of activated carbon and the yield of H₂, CH₄, the best activation parameters are as follows: the activation temperature is 800℃, the flow of steam is 3ml/min, the total activation time is 60min. When the atomic ratio of Fe/Ca was 4:1, the BET specific surface area of activated carbon is 775m²/g, the average pore size is 3.902nm, the pore volume reaches 0.488 cm³/g,the iodine value is 678mg/g, the methylene blue value can achieve 55mg/g. The yield of H₂ reaches 535mmol/g about 67.80% of the total gas in activation stage. The yield of CH₄ achieves 9.44mmol/g, accounts for 1.20% of the total gas. The yield of CO is 5.80mmol/g about 0.74% of the total gas. The yield of CO₂ achieves 238.87mmol/g, accounts for 30.27% of the total gas.The catalytic activation of CaO formed pores mainly occurred in the Ca-C interface active points, and create channels while the metal particles moves. Catalytic activation of NiO dug holes in the crystal orientation which is based on the "dissolved carbon" model. Fe₂O₃ directly involved in the reaction, it ream and improve the carbon pore structure by generating gas. Fe₂O₃ and NiO based on the melt model and mainly through the interaction of metal iron coordination catalytic the reaction of carbon and water. In the activation process the entry of Fe₂O₃ and CaO can generate CaO₂, and CaO₂ with H₂O can generate O₂, which accelerates the effect of catalytic gasification.The Fitted kinetics of steam activation of semi-cokes which were not adding catalyst and adding Fe₂O₃ were satisfied homogeneous model. For the semi-coke of adding CaO and NiO, the steam activation kinetics were satisfied condensation model. The fitted kinetics of steam-activation of semi-coke adding composite catalysts including iron-nickel and iron-calcium were satisfied homogeneous model. The decreasing order of rate constant of stream activation with adding different catalysts were: kCaO>kFe₂O₃>kNiO>kFe₂O₃+NiO> kFe₂O₃+NiO.