CuZnAl Catalyst Prepared By Complete Liquid Phasepyrolysis For Synthesis Of Higher Alcohols From Syngas

Many come from crude oil of the world’s energy production and consumption,and the"rich coal,inferior,less gas"resource structure characteristics,determines the energy rely mainly on coal in our country,a large part of the use of coal or burning power generation,thermal power consumption accounts for roughly fifty percent of the coal consumption,coal burning not only caused serious waste of resources,also brought many environmental problems and ecological problems.The low carbon alcohol prepared from the syngas prepared from coal is not only a kind of clean fuel,but also an excellent fuel quality improvement agent.It can improve the octane number of gasoline and enhance its knock resistance.One of the key links in synthesizing low carbon alcohols from syngas is the development of catalysts.At present,the catalysts developed include RH based catalyst,modified F-T catalyst,Mo based catalyst and modified methanol catalyst.In recent years,the group has been committed to syngas system low carbon alcohol catalyst research,using fully liquid of CuZnAl catalyst,prepared by the state in slurry bed CO hydrogenation experiments,accident found that by using completely liquid CuZnAl catalyst in the absence of F-T elements and the presence of alkali metal,has better ability in ethanol and low carbon alcohol synthesis.The investigation shows that the catalyst prepared by the complete liquid phase method is different from that prepared by the traditional method,and the complete liquid phase preparation technology has a unique performance when applied to the slurry bed.In order to further investigate whether the catalysts prepared by the complete liquid phase method could continue to display their unique properties in other bed types,the catalysts prepared by the complete liquid phase method were separated,extracted and dried with petroleum ether,and evaluated in a fixed-bed reactor,and it was found that their activity was low.After analysis,it was found that the catalyst obtained by direct separation and drying had good stability and produced C₂₊alcohol,but the surface carbon content of the catalyst was very high,and the catalyst activity was less than 10%.The activity and selectivity of the separated,extracted and dried catalysts were similar to that of the traditional methanol catalysts after air roasting for carbon removal,but deactivation was faster.Therefore,in this paper,on the basis of the complete liquid phase method,the pyrolysis step was added to appropriately remove some carbon species on the surface of the catalyst,so as to obtain a low carbon alcohol synthesis catalyst with excellent performance and improve the selectivity of C₂₊OH.In this paper,the influence of pyrolysis atmosphere,pyrolysis temperature,pyrolysis time and catalyst loading amount on the hydrogenation performance of catalyst CO was mainly explored.The structure of catalyst was analyzed and characterized by XRD,O₂-TPO-MS,XPS,H₂-TPR,NH₃-TPD-MS,N₂ adsorption and desorption,and the following conclusions were drawn:1.The CuZnAl catalyst prepared by the complete liquid phase method combined with the pyrolysis method retains the unique performance of the complete liquid phase technology in the slurry bed,and has been well used in the fixed bed.Different from the traditional air roasting method,this method can prolong the service life of the catalyst on the basis of retaining the ability of the catalyst to synthesize ethanol and low carbon alcohol.2.The oxygen content in the pyrolysis atmosphere,pyrolysis temperature and duration will affect the performance and structure of the catalyst.When the oxygen content is 0.1%,350℃pyrolysis for 2 h is the best pyrolysis condition,and the activity of the catalyst is always on the rise during the evaluation time.3.Different pyrolysis conditions will affect the form and quantity of copper species in the catalyst,and the presence of suitable oxidation state copper species is conducive to the generation of C₂₊alcohol.4.Carbon species are crucial to the performance of the catalyst.Excessive carbon species will cover the active sites in the catalyst and reduce its activity,but excessive elimination of carbon species will make the performance of the catalyst more inclined to methanol catalyst.5.Pyrolysis conditions will affect the strength and number of acid sites in the catalyst.When the pyrolysis temperature is low,Al OOH in the catalyst can be retained to provide more acid sites for the catalyst.There are both weak acid sites and medium strong acid sites in the catalyst,and the catalyst performance is better when there are more weak acid sites.6.The reaction temperature has a great influence on the CO hydrogenation performance and product selectivity of the catalyst,and too high reaction temperature is not conducive to the formation of ROH.