【正文】 外文資料原文 1 中文 3825字 A New LowTemperature Synthesis Route of Methanol: Catalytic Effect of the Alcoholic Solvent 1. Introduction Gasphase methanol is being produced industrially by 3040 million ton per year around the world, from CO/ CO2/H2 at a temperature range of 523573 K and a pressure range of 50100 bar, using copperzincbased oxide catalyst. Under these extreme reaction conditions, the efficiency of methanol synthesis is severely limited by thermodynamics as methanol synthesis is an extremely exothermic ,2 For example, at 573 K and 50 bar, it is calculated by thermodynamics that theoretic maximum onepass CO conversion is around 20% for flowtype reactor when H2/CO=2. Also it is reported that the onepass CO conversion in the industrial ICI process is between 15 and 25%, even if H2rich gas is used (H2/CO =5,523573 K).3 Therefore, developing a lowtemperature process for methanol synthesis, which will greatly reduce the production cost and utilize the thermodynamic advantage at low temperature, is challenging and If conversion is high enough in methanol synthesis, recycling of the unreacted syngas can be omitted and air can be used directly in the reformer, instead of pure oxygen. Generally, lowtemperature methanol synthesis is conducted in the liquid phase. The BNL method first reported by Brookhaven National Laboratory (BNL), using a very strong base catalyst (mixture of NaH, acetate), realized this continuous liquidphase synthesis in a semibatch reactor at 373403 K and 1050 bar. However, a remarkable drawback of this process is that even a trace amount of carbon dioxide and water in the feed gas or reaction system will deactivate the strongly basic catalyst soon,4,5 resulting in high cost ing from the plete purification of the syngas from reformer, and reactivation of the deactivated catalyst. This is the main 外文資料原文 2 reason stopping the mercialization of this lowtemperature methanol synthesis method. Liquidphase methanol synthesis from pure CO and H2 via the formation of methyl formate has been widely studied, where carbonylation of methanol and successive hydrogenation of methyl formate were considered as two main steps of the Palekar et al. used a potassium methoxide/copper chromite catalyst system to conduct this liquidphase reaction in a semibatch reactor at 373453 K and 3065 Although the mechanism of BNL method is still controversial, a lot of researchers think that it is similar to the mechanism However, similar to that in the BNL method, in this process CO2 and H2O act as poisons to the strong base catalyst (RONa, ROK) as well and must be pletely removed from syngas, making mercialization of lowtemperature methanol synthesis difficult. Tsubaki et al. proposed a new method of lowtemperature synthesis of methanol from CO2/H2 on a Cubased oxide catalyst using ethanol as a kind of “catalytic solvent”, by which methanol was produced in a batch reactor at 443 K and 30 This new process consisted of three steps: (1) formic acid synthesis from CO2 and H2。 (2) esterification of formic acid by ethanol to ethyl formate。 and (3) hydrogenation of ethyl formate to methanol and ethanol. Considering that the watergas shift reaction at lower temperature is easily conducted on Cu/ZnO catalyst,1525 a new route of methanol synthesis from CO/H2 containing CO2, as a more practical way of methanol synthesis, is proposed. It consists of the following fundamental steps: As formic acid was not detected in the products, we suggested the reaction path as step (2). Tsubaki et al. investigated the synthesis reaction of methanol from CO/CO2/H2, using ethanol as reaction medium in a batch reactor and found high 外文資料原文 3 selectivity for methanol formation at temperature as low as 423443 In this munication, the catalytic promoting effects of different alcohols on the synthesis of methanol from CO/ CO2/H2 on Cu/ZnO catalyst were investigated. High yields of methanol were realized while some alcohols were utilized. 2. Experimental Section The catalyst was prepared by the conventional coprecipitation method. An aqueous solution containing copper, zinc nitrates (Cu/Zn in molar ratio=1), and an aqueous solution of sodium carbonate were added simultaneously with constant stirring to 300 mL of water. The precipitation temperature and pH value were maintained at 338 K and , respectively. The resulting precipitate was filtrated and washed with distilled water, followed by drying at 383 K for 24 h and calcination at 623 K for 1 h. This precursor was then reduced by a flow of 5% hydrogen in nitrogen at 473 K for 13 h and successively passivated by 2% oxygen diluted by argon. The BET surface area for the catalyst was m2/g. The catalyst here is denoted as Cu/ZnO (A). In the experiments using reactant gas of d