【摘要】：低碳醇具有非常廣泛的應用前景,可以作為清潔的液體燃料和良好的汽油添加劑,同時它還可以作為基礎原料用于生產其他化學產品。在化石燃料資源日益減少的情況下,由合成氣催化制備低碳醇的研究受到了人們的廣泛關注。目前,對于合成氣制低碳醇的研究多集中在對催化劑的改良,但效果均不盡如人意,存在諸多問題,很難實現(xiàn)工業(yè)應用。本課題組利用自創(chuàng)的完全液相法制備了不含任何堿金屬及F-T組元的CuZnAl催化劑,在CO加氫實驗中意外發(fā)現(xiàn)其具有高的低碳醇選擇性,尤其是乙醇,但催化劑的重現(xiàn)性并不太理想,且對催化劑結構還缺乏深刻認識,因此有必要對其進行更加深入的研究。本文首先考察了高壓下熱處理溫度對催化劑結構和性能的影響,同時研究了不同的CuZnAl比例對催化劑性能的影響,最后采用提前加熱處理過的液體石蠟為熱處理和反應介質,考察了其對催化劑合成低碳醇性能的影響。本文通過XRD、H_2-TPR、BET、NH_3-TPD-MS、XPS、SEM等方法對催化劑進行了表征分析,結合催化劑的活性評價數據,進一步了解了催化劑的結構和表面性質與高C_(2+)OH選擇性的關系。得出以下主要結論:1.高溫、高壓熱處理可以提高合成乙醇的選擇性和穩(wěn)定性。熱處理條件為4.0MPa、280℃時,催化劑的乙醇選擇性隨著時間的推移持續(xù)提高,122 h后達到26.13%且保持穩(wěn)定。2.催化劑大的比表面積、適中且穩(wěn)定的Cu/Zn摩爾比、適宜含量的兩種Cu_2O、比例適當的強弱酸性位,都是提高乙醇選擇性和穩(wěn)定性的關鍵因素。3.高壓熱處理可以抑制Cu0晶粒在反應過程中長大,加強催化劑中各組分之間的相互作用,有利于尖晶石的形成,但過多的尖晶石會弱化活性組分的作用,降低催化劑的活性。4.高壓熱處理下催化劑配比影響催化劑的結構與性能。較多的Al組分含量有利于尖晶石的形成,改變Cu_2O的存在形式,降低了孔徑,使其有利于二甲醚的生成。Zn O晶粒的大小對催化劑的活性影響并不顯著,Zn組分量的增多并沒有顯著促進C_(2+)OH的生成。5.預熱處理后的液體石蠟在常壓熱處理的條件下減弱了對Cu物種的還原作用,提高了催化劑表面Cu/Zn比例,強化了Cu0-Cu+的協(xié)同作用;從而有效提高了C_(2+)OH的選擇性。但在高壓熱處理的條件下,提前熱處理液體石蠟并沒有起到促進乙醇和C_(2+)OH生成的作用。
[Abstract]:Low-carbon alcohols can be used as a clean liquid fuel and a good gasoline additive, and can also be used as a basic raw material for the production of other chemical products. With the decrease of fossil fuel resources, the synthesis of low-carbon alcohols catalyzed by syngas has attracted much attention. At present, the research on synthesis of low carbon alcohol from syngas is mainly focused on the improvement of catalyst, but the effect is not satisfactory, there are many problems, it is difficult to realize industrial application. The CuZnAl catalyst without alkali metal and F-T component was prepared by a self-made complete liquid phase method. In the CO hydrogenation experiment, it was found that the catalyst had high selectivity to low carbon alcohols, especially ethanol. However, the reproducibility of the catalyst is not ideal and the structure of the catalyst is not well understood, so it is necessary to study it more deeply. In this paper, the effect of heat treatment temperature at high pressure on the structure and performance of the catalyst was investigated, and the effects of different CuZnAl ratios on the catalyst performance were studied. Finally, the heat treatment and reaction medium of the liquid paraffin treated by preheating was used as the heat treatment and reaction medium. The effect of the catalyst on the synthesis of low-carbon alcohols was investigated. In this paper, the catalyst was characterized and analyzed by means of XRD,H_2-TPR,BET,NH_3-TPD-MS,XPS,SEM and other methods. The relationship between the structure and surface properties of the catalyst and the selectivity of C _ (2) OH was further investigated. The main conclusions are as follows: 1. High temperature and high pressure heat treatment can improve the selectivity and stability of ethanol synthesis. The ethanol selectivity of the catalyst continued to increase with time when the heat treatment condition was 4.0 MPA ~ (-1) at 280 鈩，

本文編號：2425666