Study On The Catalyst Of Co And Ni And The Performance In Ammonia Synthesis Directly From Methane And Nitrogen

Directly synthetic ammonia from methane and nitrogen, not only for theeffective way of use methane resources, will also the process of another preparation ofthe ammonia production, it can effectively reduce the costs of the traditional syntheticammonia. Based on the current situation of ammonia synthesis from natural gas, inthis thesis, we exploring a new method of one step ammonia synthesis from naturalgas. The purpose of this method is to simplify the operating equipment, reduceinvestment and pollution and improve the utilization value of the C in methane.This paper using various treatments (AC, HAC) on Coconut shell ActivatedCarbon and Coal Activated Carbon as the supports. And using the conventionalimmersion method, Co, Ni as the active component, activated carbon as the carrier tosynthesis a series of catalysts. N₂physisorption, X-ray diffraction, H₂temperatureprogrammed reduction, Scanning Electron Microscopy and H₂pulse chemicaladsorption were carried out to characterize the supports and the catalysts. And that thesupports and the catalysts were all used in ammonia synthesis, which was carried outby using nitrogen and methane as raw materials, by which the research studiesthe effect of cobalt dispersity and content of cobalt as well as the temperature on theactivity of catalysis. The activity and stability of catalysts and support were alsostudied. The tail gas of ammonia synthesis is analyzed by gas chromatography. It wasproved that ammonia can synthesis directly from nitrogen and methane under somecatalysts. The reaction products include ethane, ethylene, benzene, naphthalene,hydrogen, ammonia etc. And activated carbon under different treatments all showcertain methane catalytic convert activity and ammonia catalytic activity, but theiractivity exhibit obvious differences with different modification methods.The Co-based catalyst have considerable activity, when the activated carboncarrier have proper pores of different size, different acidities and large surface area.The highest catalytic activity for ammonia synthesis was obtained on the Co-based catalyst prepared by activity carbon(5%) with a reaction rate of1.04×10^-8mol g^-1 s^-1under the conditions of0.1MPa and600oC. The reaction temperature has obviouslyeffect on the Ni-based catalyst, Temperature is too high, will cause the Cokedeposition, constrain the catalytic activity and led to the deactivation of catalyst; whenthe content of Ni is5wt%, with the highest catalytic activity at700℃, the reactionrate is7.7×10^-9mol g^-1 s^-1. As one style catalyst for synthetic ammonia, Co-Nibimetallic composite catalyst also has its catalytic ability. The catalyst of1%Co-9%Ni/AC with the highest catalytic activity at700℃, the reaction rate is8.4×10^-9mol g^-1 s^-1, the activity could reach an ideal effect.The Cobalt, Nickel and Co-Ni bimetallic composite catalyst could catalyzemethane transforming into ethylene and ethane in synthetic ammonia with nitrogen. Inorder to control the proportion of ethylene and ethane in synthetic ammonia, thispaper attempted to append the catalyst of molybdenum loaded with molecular sieve(Mo/ZSM-5) to Co/AC to make admixture catalyst, and discussed the influence on theselectivity of transforming ethylene from methane by appending Mo/ZSM-5. Whenthe reaction temperature is between500℃to800℃, methane occurs decompositionreaction in response to the catalyst, and created ethylene, ethane, and other products atthe same time. high reaction temperature favors the production of ethylene, whileLow reaction temperature favors the production of ethane. This paper attempted toappend the catalyst of molybdenum loaded with molecular sieve (Mo/ZSM-5) toCo/AC to make admixture catalyst, significantly affects manufacturing ethylene frommethane, and the selectivity of ethylene was also improved with the increasingcontent of molybdenum, and the temperature also affects manufacturing ethylenefrom methane.