生物質(zhì)合成氣一步法制備二甲醚雙功能催化劑的研究
發(fā)布時(shí)間：2018-08-22 17:34
【摘要】：生物質(zhì)能源具有資源豐富、可再生且不增加地表CO_2循環(huán)總量的特點(diǎn),是化石能源的理想替代品。通過(guò)生物質(zhì)合成氣制備二甲醚是生物質(zhì)能源利用的一條重要途徑。本文制備了雙功能催化劑用于生物質(zhì)合成氣一步法制二甲醚�？疾炝思状己铣纱呋瘎〤uO-ZnO-MO_x (M=Zr, Al,Cr,Ti)中第三組元MO_x的影響、甲醇合成和甲醇脫水催化劑復(fù)合方式的影響、金屬鎂摻雜對(duì)催化劑穩(wěn)定性的影響。主要結(jié)果如下:一、CuO-ZnO-MO_x (M=Zr,Al,Cr, Ti)/HZSM-5 雙功能催化劑中 MO_x 對(duì)生物質(zhì)合成氣制DME的影響采用共沉淀法制備了一系列甲醇合成催化劑CuO-ZnO-MO_x (M=Zr, Al,Cr,Ti)。結(jié)果表明CuO-ZnO-Zr02催化劑有最大的SBET和銅比表面。經(jīng)還原和反應(yīng)后的CuO-ZnO-MO_x催化劑,表面銅元素均以Cu0形式存在。將CuO-ZnO-MO_x與HZSM-5按顆�；旌戏绞浇M成雙功能催化劑用于生物質(zhì)合成氣一步法制DME。結(jié)果顯示CuO-ZnO-ZrO_2/HZSM-5催化劑具有最高的CO轉(zhuǎn)化率和DME收率。CO轉(zhuǎn)化率隨著銅比表面積的增加而升高,但兩者并不是線性關(guān)系。水氣反應(yīng)產(chǎn)生的原位H2能促進(jìn)CO加氫,提高DME的收率,這對(duì)具有“貧氫”特性的生物質(zhì)合成氣制DME過(guò)程尤為重要。二、催化劑復(fù)合方式對(duì)生物質(zhì)合成氣制DME的影響考察了四種不同復(fù)合方式(分層、顆�；旌�、粉末混合和核殼結(jié)構(gòu))制備的雙功能催化劑CuO-ZnO-Al_2O_3/HZSM-5對(duì)生物質(zhì)合成氣制DME的影響。復(fù)合方式影響反應(yīng)活性位的性質(zhì);復(fù)合方式影響雙功能催化劑的宏觀結(jié)構(gòu),進(jìn)而影響兩組分之間的協(xié)同作用。顆粒混合方式所得催化劑具有最高的CO轉(zhuǎn)化率和DME收率,而分層方式的CO轉(zhuǎn)化率和DME收率最低。復(fù)合方式對(duì)催化性能的影響進(jìn)一步驗(yàn)證了水氣反應(yīng)產(chǎn)生的原位H2可以促進(jìn)甲醇的生成,從而獲得更高的DME收率。甲醇合成催化劑中Cu晶粒的增大是雙功能催化劑失活的主要原因,而反應(yīng)中H2O的生成則是導(dǎo)致Cu晶粒增大的主要因素。此外,還考察了反應(yīng)溫度、壓力和空速對(duì)催化性能的影響。三、MgO的添加對(duì)催化劑穩(wěn)定性的影響通過(guò)等體積浸漬法制備了 MgO改性的CuO-ZnO-Al_2O_3催化劑,將其與HZSM-5按顆粒混合方式得到雙功能催化劑。實(shí)驗(yàn)結(jié)果表明雙功能催化劑中銅基催化劑的失活導(dǎo)致雙功能催化劑活性下降,而Cu晶粒長(zhǎng)大是銅基催化劑失活的主要原因。HZSM-5表面有少量的積炭,但不是催化劑失活的主要因素。MgO的添加增加了 CuO的還原難度,但抑制催化劑中Cu粒徑的長(zhǎng)大,降低催化劑失活的速率。
[Abstract]:Biomass energy is an ideal substitute for fossil energy because it is rich in resources, renewable and does not increase the total amount of surface CO_2 cycle. The synthesis of dimethyl ether from biomass syngas is an important way to utilize biomass energy. In this paper, bifunctional catalysts were prepared for one-step synthesis of dimethyl ether from biomass syngas. The effects of the third component (MO_x) in methanol synthesis catalyst CuO-ZnO-MO_x (Mn-Zr-Al-Cr-Ti), the combination of methanol synthesis and methanol dehydration catalyst, and the influence of magnesium doping on the stability of the catalyst were investigated. The main results are as follows: (1) the effect of MO_x on the synthesis of DME from biomass syngas in CuO-ZnO-MOx (MZZrO- AltCr, Ti) / HZSM-5 bifunctional catalysts was studied. A series of methanol synthesis catalysts, CuO-ZnO-MO_x (Mzororcalori, AlniCr-Ti), were prepared by coprecipitation method. The results show that the CuO-ZnO-Zr02 catalyst has the largest SBET and copper specific surface. After reduction and reaction, copper on the surface of CuO-ZnO-MO_x catalyst exists in the form of Cu0. The bifunctional catalyst composed of CuO-ZnO-MO_x and HZSM-5 was used in the one-step synthesis of biomass syngas. The results showed that CuO-ZnO-ZrO_2/HZSM-5 catalyst had the highest CO conversion and DME yield. Co conversion increased with the increase of copper specific surface area, but the relationship between them was not linear. In situ H2 produced by water gas reaction can promote CO hydrogenation and improve the yield of DME, which is particularly important for the production of DME from biomass syngas with "hydrogen deficiency" characteristics. Secondly, the effect of catalyst recombination on the production of DME from biomass syngas was studied. The effects of four different ways (stratification, particle mixing, powder mixing and core-shell structure) on the production of DME from biomass syngas were investigated. The compound mode affects the properties of the reactive sites and the macrostructure of the bifunctional catalysts and the synergism between the two components. The catalyst obtained by particle mixing has the highest CO conversion and DME yield, but the lowest CO conversion and DME yield is obtained by stratified method. The effect of the composition method on the catalytic performance further verified that in situ H2 produced by the water gas reaction could promote the formation of methanol, thus obtaining a higher yield of DME. The increase of Cu grain in methanol synthesis catalyst is the main reason for the deactivation of the bifunctional catalyst, while the formation of H2O in the reaction is the main factor leading to the increase of Cu grain. In addition, the effects of reaction temperature, pressure and space velocity on the catalytic performance were investigated. The influence of the addition of MgO on the stability of the catalyst the MgO modified CuO-ZnO-Al_2O_3 catalyst was prepared by the equal volume impregnation method. The bifunctional catalyst was prepared by mixing it with HZSM-5 in a granular manner. The experimental results show that the deactivation of Cu-based catalyst in bifunctional catalyst leads to the decrease of activity of the bifunctional catalyst, and Cu grain growth is the main reason for the deactivation of Cu-based catalyst. There is a small amount of coking on the surface of HZSM-5. But it is not the main factor of catalyst deactivation. The addition of MgO increases the reduction difficulty of CuO, but inhibits the growth of Cu particle size in the catalyst and reduces the deactivation rate of the catalyst.
【學(xué)位授予單位】：上海應(yīng)用技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36;TQ223.24
本文編號(hào)：2197823
[Abstract]:Biomass energy is an ideal substitute for fossil energy because it is rich in resources, renewable and does not increase the total amount of surface CO_2 cycle. The synthesis of dimethyl ether from biomass syngas is an important way to utilize biomass energy. In this paper, bifunctional catalysts were prepared for one-step synthesis of dimethyl ether from biomass syngas. The effects of the third component (MO_x) in methanol synthesis catalyst CuO-ZnO-MO_x (Mn-Zr-Al-Cr-Ti), the combination of methanol synthesis and methanol dehydration catalyst, and the influence of magnesium doping on the stability of the catalyst were investigated. The main results are as follows: (1) the effect of MO_x on the synthesis of DME from biomass syngas in CuO-ZnO-MOx (MZZrO- AltCr, Ti) / HZSM-5 bifunctional catalysts was studied. A series of methanol synthesis catalysts, CuO-ZnO-MO_x (Mzororcalori, AlniCr-Ti), were prepared by coprecipitation method. The results show that the CuO-ZnO-Zr02 catalyst has the largest SBET and copper specific surface. After reduction and reaction, copper on the surface of CuO-ZnO-MO_x catalyst exists in the form of Cu0. The bifunctional catalyst composed of CuO-ZnO-MO_x and HZSM-5 was used in the one-step synthesis of biomass syngas. The results showed that CuO-ZnO-ZrO_2/HZSM-5 catalyst had the highest CO conversion and DME yield. Co conversion increased with the increase of copper specific surface area, but the relationship between them was not linear. In situ H2 produced by water gas reaction can promote CO hydrogenation and improve the yield of DME, which is particularly important for the production of DME from biomass syngas with "hydrogen deficiency" characteristics. Secondly, the effect of catalyst recombination on the production of DME from biomass syngas was studied. The effects of four different ways (stratification, particle mixing, powder mixing and core-shell structure) on the production of DME from biomass syngas were investigated. The compound mode affects the properties of the reactive sites and the macrostructure of the bifunctional catalysts and the synergism between the two components. The catalyst obtained by particle mixing has the highest CO conversion and DME yield, but the lowest CO conversion and DME yield is obtained by stratified method. The effect of the composition method on the catalytic performance further verified that in situ H2 produced by the water gas reaction could promote the formation of methanol, thus obtaining a higher yield of DME. The increase of Cu grain in methanol synthesis catalyst is the main reason for the deactivation of the bifunctional catalyst, while the formation of H2O in the reaction is the main factor leading to the increase of Cu grain. In addition, the effects of reaction temperature, pressure and space velocity on the catalytic performance were investigated. The influence of the addition of MgO on the stability of the catalyst the MgO modified CuO-ZnO-Al_2O_3 catalyst was prepared by the equal volume impregnation method. The bifunctional catalyst was prepared by mixing it with HZSM-5 in a granular manner. The experimental results show that the deactivation of Cu-based catalyst in bifunctional catalyst leads to the decrease of activity of the bifunctional catalyst, and Cu grain growth is the main reason for the deactivation of Cu-based catalyst. There is a small amount of coking on the surface of HZSM-5. But it is not the main factor of catalyst deactivation. The addition of MgO increases the reduction difficulty of CuO, but inhibits the growth of Cu particle size in the catalyst and reduces the deactivation rate of the catalyst.
【學(xué)位授予單位】：上海應(yīng)用技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36;TQ223.24
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，本文編號(hào)：2197823
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