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首页> 外文学位 >THE SYNTHESIS OF LOW MOLECULAR WEIGHT OLEFINS OVER COPRECIPITATED IRON-MANGANESE CATALYSTS (FISCHER-TROPSCH SYNTHESIS, CARBON MONOXIDE HYDROGENATION).
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THE SYNTHESIS OF LOW MOLECULAR WEIGHT OLEFINS OVER COPRECIPITATED IRON-MANGANESE CATALYSTS (FISCHER-TROPSCH SYNTHESIS, CARBON MONOXIDE HYDROGENATION).

机译：精密铁锰催化剂上的低分子量烯烃的合成（费-托合成，碳一氧化碳加氢）。

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The synthesis of low molecular weight olefins (C(,2)-C(,4)) from hydrogen and carbon monoxide has been investigated over unsupported iron-manganese catalysts. Nine iron-manganese catalysts with different atomic Mn/Fe ratios were prepared by coprecipitation of iron and manganese nitrates. The atomic Mn/Fe ratios of the catalysts ranged from 0/100 to 11.8/100. The technique was capable of preparing catalysts with reproducible atomic Mn/Fe ratios. The major bulk phase of the calcined iron-manganese catalysts was hematite ((alpha)-Fe(,2)O(,3)). The average particle size of hematite in the catalysts decreased as the atomic ratio of Mn/Fe increased. In addition, the range of the (alpha)-Fe(,2)O(,3) crystallite size for these catalysts was 15-24 nm.; The catalysts were evaluated in a conventional bench-scale fixed-bed reactor system. A period of 12 hours was generally required to stabilize activity and selectivity at the operating conditions investigated: 473-483 K, 1465 kPa, 2/1:H(,2)/CO, and 1.08 cm('3)g('-1)s('-1).; A catalyst reduction study in a thermogravimetric analysis (TGA) system showed that hydrogen reduction at 673 K and ambient pressure for 8 hours was sufficient to activate the catalyst. The results from an evaluation of the effect of catalyst bed dilution on activity and selectivity indicated that a volumetric dilution ratio of Denstone 57/catalyst of 4/1 was effective in removing the global heat of reaction in the catalyst bed and in modifying the C(,2)-C(,4) olefin selectivity. Experimental data on the influence of the catalyst pretreatment on activity and selectivity with hydrogen, carbon monoxide, and synthesis gas (H(,2)/CO ratios 1, 2, and 3) indicated that the hydrogen pretreatment resulted in a more stable catalyst activity and higher olefin selectivity (i.e., 70 mole percent).; The experimental results from carbon monoxide hydrogenation at the standard operating conditions (i.e., 2/1:H(,2)/CO, 1465 kPa, 1.0 cm('3)g('-1)s('-1) and 503 K) indicated that the catalyst activity generally decreased as the manganese concentration of the catalyst increased; however, the C(,2)-C(,4) olefin selectivity was significantly enhanced with a small amount of manganese in the catalyst (i.e., 2.5 Mn/100 Fe). Data on selective chemisorption of hydrogen and carbon monoxide at 292 K for these iron-manganese catalysts indicated that the carbon monoxide uptake was much higher than the hydrogen uptake.
机译：在无载体的铁锰催化剂上，已经研究了由氢气和一氧化碳合成低分子量烯烃（C（，2）-C（，4））的方法。通过共沉淀硝酸铁和硝酸锰，制备了九种具有不同锰/铁原子比的铁锰催化剂。催化剂的原子Mn / Fe比范围为0/100至11.8 / 100。该技术能够制备具有可再现的原子Mn / Fe比的催化剂。煅烧的铁锰催化剂的主要本体相是赤铁矿（α-Fe（，2）O（，3））。催化剂中赤铁矿的平均粒径随着Mn / Fe原子比的增加而减小。另外，这些催化剂的α-Fe（，2）O（，3）微晶尺寸范围为15-24nm。在常规的台式规模固定床反应器系统中评估催化剂。通常需要12小时的时间来稳定所研究的操作条件下的活性和选择性：473-483 K，1465 kPa，2/1：H（，2）/ CO和1.08 cm（'3）g（'- 1）s（'-1）.;在热重分析（TGA）系统中进行的催化剂还原研究表明，在673 K和环境压力下将氢气还原8小时足以活化催化剂。评估催化剂床层稀释对活性和选择性的影响的结果表明，Denstone 57 /催化剂的体积稀释比为4/1，对于去除催化剂床层中的整体反应热和改性C（ ，2）-C（，4）烯烃的选择性。关于催化剂预处理对氢气，一氧化碳和合成气的活性和选择性的影响的实验数据（H（，2）/ CO比率为1、2和3）表明，氢气预处理导致更稳定的催化剂活性和更高的烯烃选择性（即70摩尔％）。在标准操作条件下（即2/1：H（，2）/ CO，1465 kPa，1.0 cm（'3）g（'-1）s（'-1）和503）进行一氧化碳加氢的实验结果K）表明，随着催化剂锰浓度的增加，催化剂的活性通常降低。但是，在催化剂中添加少量锰（即2.5 Mn / 100 Fe）后，C（，2）-C（，4）烯烃的选择性大大提高。这些铁锰催化剂在292 K下选择性吸收氢和一氧化碳的数据表明，一氧化碳的吸收量远高于氢的吸收量。

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