Study On Hydrogen-rich Gas From Catalytic Steam Reforming Of Tar In RCOG

China is the world's largest producer of cokes,which can produce about 203.2 billion m3 of COG every year,however 20%of COG is direct emitted.The temperature of RCOG in the riser pipe outlet is 650-850 ?,the cooled tar will cause pipeline corrosion.Traditionally COG is cooled down by ammonia spraying and separated such as benzene,toluene and other hydrocarbon compounds,leading to large amounts of sensible heat wasted,chemical energy wasted and environmental pollution.Currently,the pressure swing adsorption(PSA)technology as an industrial process has been applied in advanced iron and steel factory.However,there is abundance of other energetic components left in RCOG which contains tar and CH4,etc.In the way of steam reforming of hydrocarbon compounds,the amount of hydrogen produced from RCOG will be increased.So the research advice to product rich hydrogen in the way of catalytic steam reforming of tar.On the basis of the process,we mainly discuss the following content:Firstly,the thermodynamic analysis of steam reforming of 1-Methylnaphthalene and RCOG was investigated.The effect of temperature,S/C and pressure on the reforming reaction was also researched.Secondly,Ni/Al2O3,Ni/MgO/Al2O3,Ni/C12A7 and Ni/MgO/C12A7 were prepared by high temperature roasting and step impregnation method,these catalysts were characterized by BET and XRD and tested activity,in order to find the best catalyst.Thirdly,preparation methods(high temperature roasting,sol-gel self-propagating and coprecipitation)and calcination temperature(950?,1150? and 1350?)were researched to find the relationship with structure and performance of catalysts over Ni/MgO/C12A7.Fourthly,in order to study the effect of operation parameters on the reforming reaction,we chosen different S/C,temperature and LHSV as reaction conditions.The study results in the paper can be concluded as following points.(1)Thermal cracking reaction occurs mainly in the low temperature,steam reforming reaction and the dry reforming reaction occur in high temperature.The hydrogen yield was increased and the carbon yield was reduced with the improvement of S/C.The atmospheric pressure and negative pressure are good for steam reforming.The steam reforming of tarbehaved better in RCOG.(2)The catalysts were supported by C12A7 consisted of NiO,MgO and NiO-MgO.The surface areas of these catalysts are relatively small.The catalysts were supported by ?-Al2O3 mainly consisted of NiAl2O4 and MgAl2O4,the surface areas were larger.The C characteristic peak was not obvious and the minimal Ni grain was found from Ni/MgO/C12A7 after reforming reaction.The results showed that Ni/MgO/C12A7 activity was the highest,and the gas composition basically the same in different catalysts.(3)There was interaction between active substances and additives in Ni/MgO/C12A7-rj and Ni/MgO/C12A7-gw1350.The catalysts were prepared by sol-gel self-propagating and coprecipitation method has high surface areas.The catalyst was prepared by high temperature roasting method activity was stronger than others which.C12A7 structure can be obtained only over 1000? under high temperature roasting method,Ni/MgO/C12A7 got the strongest activity under 1350 ? calcination temperature.(4)With the increase of S/C and temperature,hydrogen yield and gas containing carbon yield were increased.With the decrease of LHSV,hydrogen yield and gas containing carbon yield were increased The hydrogen yield remained stable in stability experiment over Ni/MgO/C12A7,which demonstrated Ni/MgO/C12A7 has high catalytic stability.