Catalysts To Synthesis Ethylene Of Selective Hydrogenation Of Acetylene And Its Reactive Technology

Acetylene selective hydrogenation reaction and the catalyst is the current hot spot concern, domestic and foreign reports be more, but the research mainly used to remove petroleum hydrocarbon pyrolysis process of trace ethylene (mole fraction x0.5%～2%) acetylene, diene, in order to prevent poisons the catalyst used in subsequent ethylene polymerization processes, but the catalytic performance for selective hydrogenation of acetylene to ethylene under the conditions of "high concentration acetylene, high space velocity" is rarely explored, the corresponding large-scale industrial application is not reported. In this paper, a series of Pd/SiO2 catalysts were prepared by the incipient wetness impregnation method. The loading of the catalyst Pd, the type of assistant catalyst, the ratio of Pd and assistant catalysts, catalyst life were investigated. We explored the optimum reaction conditions of selective hydrogenation of acetylene to ethylene by the reaction temperature, H2/C2H2 flow ratio, reaction space velocity. The Excellent catalytic performance of catalyst was characterized by BET, TG, XRD, EDS, TEM, SEM and TPD.The experimental results showed, Acetylene hydrogenation was carried out in QGF2-type small-scale fixed-bed catalytic reactor, The products were analyzed by GC7890ⅡFID thermal conductivity gas chromatography detector. Screened the loading of the catalyst Pd 0.3wt%, when the loading of Pd was 0.3wt%, the conversion rate of acetylene closed to 100%, the yield of ethylene was up to 76.5%; assistant reagents Ti, Mg, La, Ce, Cu could significantly increased the selectivity of ethylene to Pd/SiO2 Catalyst, in which Ti, Mg of the most obvious, Ti, Mg the best ratio for npd:nx= 1:1, the yield of ethylene increased respectively by 8.7% and 7.6%. Explored the optimum conditions of the selective hydrogenation of acetylene to ethylene, reaction temperature 110℃, feed gas ratio of C2H2: H2= 1:4, space velocity of 15000h-1. The SiO2 surface area is 275-300cm2/g with moderate surface area and pore size distribution by BET, the calcinations temperature is 400℃by TG, Compared Pd-Ti/SiO2 with Pd/SiO2 the surface area increases, the surface of catalysts distributed evenly by SEM, the titanium oxide in Pd-Ti/SiO2 catalyst was amorphous, and the addition of Ti reduced the particle size of Pd significantly by TEM, EDS. The Pd was the face-centered cubic crystal; the existence of TiO2 was in the form of amorphous in Pd-Ti/SiO2 catalyst, the catalyst of Pd/SiO2, Pd-Ti SiO2 were weak acid, it could inhibit ethylene hydrogenation to ethane, the Pd-Ti/SiO2 ( npd:nTi= 1:1) is a kind of good catalyst.The petroleum is a shortage and non-renewable strategic resource, the main downstream products of acetylene industrial have a low PVC price, but petroleum and ethylene industry have much higher added value. It is great significance to adjustment the industrial structure of calcium carbide process for developing a high concentration selective hydrogenation of acetylene.