生物质热化学转化所得生物油的催化改质

发布时间：2018-09-05 07:56

【摘要】：本文以辛酸作为生物质热解所得生物油的模型化合物,探讨了催化加氢以及催化酯化这两种生物油提质手段对辛酸脱氧的影响。对于辛酸催化加氢,当氢气压力为3MPa,反应温度为320oC,催化剂为5%Ni-ZrO2时,辛酸的转化率最高为92.79%,主要产物是辛酸通过加氢生成辛醛-辛醛脱羰而产生的庚烷,其收率为69.68%;反应过程中还有少量的轻烃、辛烷、辛醇、辛酸辛酯等产物产生。相同条件下,当催化剂为掺杂10 wt.%Mo改性的10Mo/Ni-ZrO2时,辛酸的转化率为100%,此时主要产物为辛烷,收率为77.07%;同时还有轻烃、庚烷、辛烯、辛醛、辛醇、辛酸辛酯等产生,收率分别为2.31%、10.67%、0.99%、3.56%、4.89%和1.10%。对Mo掺杂前后的镍基催化剂进行了N2吸附-脱附、TEM、XRD、H2-TPR、NH3-TPD以及H2-TPD表征,得出Mo的掺杂可以显著增加催化剂的比表面积,增强催化剂的酸性,提高催化剂的H2吸附量,并使得ZrO2载体由立方型转变为单斜型。以上作用都有利于提高镍基催化剂的催化活性,增强催化剂对H2的吸附性能,从而导致了反应向辛醛加氢生成辛醇-辛醇脱水生成辛烯-辛烯加氢生成辛烷方向进行,继而导致了辛酸加氢主要产物由庚烷向辛烷的转变。对于辛酸催化酯化,甲醇作为醇助剂,当反应温度为160oC,甲醇/辛酸的摩尔比为4.5:1时,550oC焙烧得到的SO_4~(2-)/Al_2O_3的催化效果最好,辛酸的转化率最高为92.56%,目标产物-辛酸甲酯的最高收率为89.08%。同等条件下,当催化剂为经SiO2掺杂改性后的SO_4~(2-)/Al_2O_3-SiO2(Al/Si摩尔比为5:1),记做SAS-5时,辛酸的转化率增加到99.11%,同时辛酸甲酯的收率上升为99.07%,没有其他副产物产生。对改性前后的催化剂进行了N2吸附-脱附、XRD、红外、热重、原位吡啶红外吸附等一系列表征,得出掺杂SiO2后,使得催化剂的比表面积显著增加,同时还会抑制Al2(SO4)3晶型的形成,并有利于催化剂表面SO42-的形成,增强催化剂的酸性;此外SiO2的掺杂还有利于增强SO42-与氧化铝的相互作用,增强催化剂的稳定性并延长使用寿命,使得SAS-5催化剂在循环使用了9次之后仍能保持较高的催化活性。循环使用后的催化剂的B酸位的量明显下降,而L酸位的量变化不大,说明B酸位对于辛酸的催化酯化起着主要作用;同时,B酸位的流失也是催化剂失活的主要原因。
[Abstract]:In this paper, octanoic acid was used as a model compound of bio-oil from biomass pyrolysis, and the effects of catalytic hydrogenation and catalytic esterification on the deoxidation of octanoic acid were discussed. The product is heptane produced by decarbonylation of octanaldehyde to octanaldehyde in 69.68% yield, and a small amount of light hydrocarbons, octane, octanol, octanoate and other products are produced in the reaction process. The yields of light hydrocarbons, heptane, octene, octanaldehyde, octanol and octyl octoate were 2.31%, 10.67%, 0.99%, 3.56%, 4.89% and 1.10% respectively. ZrO2 supports were converted from cubic to monoclinic by increasing the acidity of the catalysts, increasing the H2 adsorption capacity of the catalysts. All the above actions were conducive to improving the catalytic activity of the nickel-based catalysts and enhancing the adsorption capacity of the catalysts for H2, resulting in the hydrogenation of octanol to octanol and the dehydration of octanol to octene and octene to octene. For the catalytic esterification of octanoic acid, methanol is used as alcohol promoter. When the reaction temperature is 160oC and the molar ratio of methanol to octanoic acid is 4.5:1, the catalytic effect of SO_4~ (2-) / Al_2O_3 from 550oC calcination is the best, and the conversion of octanoic acid is 92.56% and the target product-Al_2O_3 is the best. The highest yield of methyl octanoate is 89.08%. Under the same conditions, when the catalyst is SO_4 ~ (2-) / Al_2O_3-SiO_2 (Al/Si molar ratio is 5:1) modified by SiO_2 doping, the conversion of octanoic acid increases to 99.11% as SAS-5, and the yield of methyl octanoate increases to 99.07% without any by-products. A series of characterizations, such as adsorption-desorption, XRD, IR, TG, in-situ pyridine infrared adsorption, etc., show that doping SiO2 can significantly increase the specific surface area of the catalyst, inhibit the formation of Al2 (SO4) 3 crystal form, and facilitate the formation of SO42 - on the surface of the catalyst, enhance the acidity of the catalyst; in addition, SiO2 doping is also conducive to the enhancement of SO42 - and alumina. The stability of the SAS-5 catalyst was enhanced and its service life was prolonged by the interaction. The activity of the SAS-5 catalyst remained high after 9 cycles. The loss of acid sites is also the main reason for catalyst deactivation.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE667

【参考文献】