Study On The Promoter Effect Of Cu₂O As Catalyst For Formaldehyde Acetylation

1,4-Butynediol?short for BYD?is a versatile basic organic raw chemicals.1,4-butanediol?BDO?,tetrahydrofuran?THF?,?-butanolide?GBL?,polyurethane?PU?,polybutylene terephthalate?PBT?and a series of high value-added chemicals can be prepared by 1,4-butynediol.1,4-butenediol plays an important role as a chemical raw material connecting coal primary chemicals with high value-added chemicals in great market demand.In the industrial production of BYD,alkyne aldehyde process using formaldehyde and acetylene as raw materials and copper and bismuth catalysts were used.In the process of formaldehyde acetylation,the initial Cu²⁺ oxides or base salts need to be transformed into active species through complex chemical changes,and it is speculated that such a transformation process includes:selective reduction of Cu²⁺ to Cu+ by formaldehyde;the formation of cuprous acetylide by Cu+ with acetylene two processes.Due to the uncontrollable reduction of Cu²⁺ to Cu+,Cu+ compound is directly selected as the active precursor,which is more conducive to the formation of active species of Cu²⁺.This work by Cu?NO₃?₂ as the source of copper,Na OH as precipitating agent,sodium ascorbic acid as reducing agent,using liquid phase reduction method,by changing the precipitating agent and reducing agent was prepared by adding order series of Cu₂O of different structure,and the introduction of metal oxide additives in the Cu₂O,studied the preparation conditions and metal oxide additives on the physicochemical properties and catalytic Cu₂O formaldehyde acetylene the influence of the reaction.The main research contents:1?The addition order of precipitant and reductant has great influence on the physicochemical properties of Cu₂O and the catalytic performance of formaldehyde acetylation.Na OH was added first,and then sodium ascorbate was added.Cu₂O had high crystallinity and large particle size,and it wasdifficult to be converted into the active species;sodium ascorbate was added first,then Na OH was added,and Cu₂O was excessively reduced to inactive metal Cu,both of which resulted in low activity of the catalyst.After Na OH.2?On the basis of optimizing Cu₂O structure,the crystallinity and reducibility of Cu₂O were adjusted by doping Mg O,Al2O3 and Fe₂O₃in Cu₂O.After the introduction of Mg O in Cu₂O,the crystallinity of Cu₂O hardly changed,and the interaction between Mg O and Cu₂O was weak,which had little influence on the acetylation performance of Cu₂O.After the introduction of Al2O3,the crystallinity of Cu₂O decreased significantly,and the reducibility moved to the direction of low temperature,increasing the exposed Cu+ active site,and the alkylation activity of the catalyst increased.After the introduction of Fe₂O₃,the crystallinity of Cu₂O decreased significantly,and the strong interaction between Fe₂O₃and Cu₂O was beneficial to the formation of the active species of cuprous acetylene,showing the optimal catalytic performance.3?The amount of Fe₂O₃introduced on the surface of Cu₂O was modulated.It was found that Fe₂O₃was deposited on the surface of Cu₂O and reacted with Cu₂O to form Cu O species.The strong oxidizability of Fe3+improves the stability of Cu+ under reducing atmosphere.A suitable amount of Cu+ active sites can be obtained by suitable Fe₂O₃,so that Cu₂O exhibits optimal alkyneization performance.When the content of Fe₂O₃is too high,Cu₂O is transformed into Cu O,and it is combined with Fe₂O₃.The surface exposed Cu+ decreases and the activity decreases.