Nickel Catalysts For Vapour Phase Carbonylation Of Methanol To Acetic Acid At Low Pressure

The carbonylation of methanol to synthesize acetic acid is a comparatively mature technique currently that developed by Monsanto, utilizes a homogeneous Rh-I based catalyst for implementing the reaction in the presence of methyl iodide. But the liquid homogeneous process has several disadvantages, such as corrosive attack to the reactors, difficult separation of products from the catalyst, limited supply of Rh, etc.. Recently, the studies of vapor phase carbonylation show good foreground in solving above-mentioned problems, and has virtue of good production efficiency and low on-stream pressure as well,so exploratory research on related fields are drawing more and more attention from both industrial and academic sectors. Since nickel is inexpensive with superior catalytic activity, active carbon has better specific area, in this paper, a series of nickel-loaded catalysts (Ni/AC )were prepared and studied systematically, then bimetal catalysts were carefully examined and compared, technological conditions of tri-metals catalyst were observed, finally, exploratory researches were carried out on some possible influencing factors in the oxo process.The studies of this thesis mainly include the following aspects:1. Ni/AC catalysts were prepared by dip-molding, and appropriate ways of steep, desiccation, heat and activation treatment were ascertained .It is discovered that the optimal temperature of heat and H2 activation treatment, which turned out to be 400℃ and 550℃, conduced to increasing number of active centers and enhancing the yield of acetic acid .2.Under low pressure vapor phase and Ni/AC catalysts, orthogonal experiments L9(34) were utilized to inspect factors affecting the oxo process. According to the results, the content of Ni and reaction temperature are crucial in the carbonylation, the increase of both standards could impove catalytic activity and by-products .3. Under the optimal reaction conditions: n( CO/MeOH/CH3I)=60/20/1, 1MPa ,300℃, contact time is 10gcat·h/mol and the content of Ni is 8.5%(wt),a maximum activity is achieved. The total selectivity of carbonyl products is more than 90%,the conversion of methanol reaches 92.85% and the yield of carbonyl products is 48.19%.Compared with the results from Institute of Coal Chemistry, which reaction conditions are 1.5MPa,280℃, 2.5%,the yield of acetic acid in this paper is increased by 1.83%,while the selectivity of by-products is decreased by 12.26%.4. A series of Ni-based bimetallic catalysts were investigated under low pressure vapor-solid phase . It is revealed that the additive of Cu,Zn,Sn,La into Ni/AC facilitated the reaction while Fe ,Mo,Pb restrained it.5. The simultaneous addition of Cu and Zn to Ni/AC has better catalytic activity in the oxo process of methanol to acetic acid, the appropriate ratio of the three metals is 5%Ni:5%Zn:5%Cu(wt),under the optimal conditions, the conversion of methanol reaches 94.58%,and the total yield of carbonyl products is 51.26%.6. Exploratory researches on some possible influencing factors in the oxo process revealed that the addition of rare earth could shorten the induction period, hydrogen could suppress the catalytic activity, increasing of pressure contributed little to the oxo synthesis, and methyl iodide as a promoter was pivotal.