Study Of High Stability Mesoporous Catalyst For Synthesis Of 1,4-butynediol

1,4-butynediol(BD)is an important organic chemical intermediate,which can derive many kinds of organic products,such as butadiene,butanediol,tetrahydrofuran,etc,and is widely used in industry,agriculture,and pharmaceuticals.These products,such as butanediol(BDO)and tetrahydrofuran(THF),can further produce engineering plastics,elastic fibers,pesticides and so on.In recent years,the demand for BD and BDO in China is increasing with the development of its downstream industry chain,and has reached 700,000 tons in 2017.At present,the BD,using formaldehyde and acetylene as raw materials,is prepared by Reppe method with the action of copper-based catalyst.China has abundant coal resource,mature technology for producing acetylene by calcium carbide method.China has a huge advantage in the production of BD by the Reppe method because raw materials of formaldehyde and acetylene are cheap and easy to get.However,butynediol industry started relatively late,and the technology is not advanced enough in China.Most of the high-efficiency catalysts used in BD synthesis depend on the import.Therefore,it is of great practical significance to develop the high efficiency catalyst that our country will possess advanced catalyst preparation technology.At present,traditional catalysts show the problems of poor stability and low life expectancy,and they are easily deactivation because of carbon deposition.The traditional catalyst often needs to be replaced in the industrial production.Mesoporous materials are considered to be excellent catalysts and catalyst support due to their unique properties and its have been used in many catalytic reactions.At present,mesoporous catalysts have been widely used in Fischer Tropsch synthesis,methane,methanol to olefin and aromatic hydrocarbons and other fields.However,its application in the field of alkyne aldehyde is rarely reported.This project intends to introduce mesoporous materials to alleviate carbon deposition and catalyst deactivation during the conversion process of carbon containing compound,and improve the activity and stability of the catalyst.In this thesis,Cu-based catalysts for formaldehyde acetylation were prepared using mesoporous materials as carriers.The catalysts were characterized by a series of analytical methods.The structural characteristic of the catalysts and their effect on catalyst activity,selective and lifetime were analyzed in the experiment.This result provides some basic data for the further development of the catalyst.The main findings of this paper are as follows:Typical mesoporous materials,namely mesoporous Al2O3,MCM-41 and CMK-3were respectively selected among the novel mesoporous metal oxides,mesoporoussilicon-based materials and mesoporous carbons.Mesoporous catalysts were prepared by impregnating copper components into mesoporous materials.The performance of the catalyst was evaluated in slurry bed reactor with stirring at low pressure.The results of characterization and performance evaluation showed that the catalyst with mesoporous Al2O3 exhibited good performance in activity,selectivity and stability.Then,mesoporous Cu-based catalysts were prepared using home-made mesoporous Al2O3 by sol-gel method as carrier,and were used to further examine the effect of process conditions on the performance of the catalyst.Mesoporous Cu-based catalysts were prepared by Solvent(ethanol)Evaporation Induced Self-Assembly(EISA)and equal volume impregnation methods,respectively.The experimental and analytical results revealed that the catalysts prepared by the impregnation method had low dispersion of Cu,which accumulates on the catalyst surface in the form of Cu O.And the reduction ability is poor because of interaction between Cu O and Al2O3.The catalysts prepared by ethanol Evaporation-induced self-assembly displayed well dispersivity and appropriate reducibility,so that Cu2+was effectively reduced to Cu+.The Cu-based catalysts exhibited better catalytic performance due to the uniform dispersion of copper acetylide active center which was formed by the combination of Cu+ and acetylene.Mg O is introduced to increase the activity of the catalyst and increase the catalyst's ability to resist carbon deposition.The influence of the introduction of Mg on the structure and properties of mesoporous catalyst was emphatically analyzed by means of BET,XRD,TPR,FT-IR and TEM.The results demonstrate that the mesoporous Cu O/Mg O catalyst can accelerate the reaction of formaldehyde and acetylene,decrease the selectivity of 1,4-butynediol and generate large amounts of propynyl alcohol.The Cu-Mg-Al composite mesoporous catalyst,by adding a small amount of Mg O to modify,exhibits excellent performance.