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铁化合物对C + CO_2 <-> 2CO反应的催化作用
Thesis Advisor储绍彬
Degree Grantor中国科学院研究生院

本文在总结了前人的研究成果基础上,比较系统地研究了铁化合物、铁化合物与碱金属化合物等所组成的混合物对Boudouard反应C + CO_2 → 2CO的催化作用。并详细研究了各种反应条件对其活性的影响,而且对催化反应的机理及动力学参数进行了初步探讨和测定。研究结果表明:铁化合物对Boudouard反应具催化性;铁的催化性与铁化合物和C的混合方式有关,吸附法制得样品略高于浸渍法高于干法混合制得的样品的活性;铁的催化作用与其含量关系不大,当铁的浓度高于0.02% 时即具有相对较高的活性;干法混合时,铁化合物中的阴离子对其有影响:FeCl_3 > FeCl_2 > Fe_2 O_3 > Fe > Fe_2 (SO_4)_3 > FeSO_4而湿法浸渍则基本上没有影响;当在铁化合物中加入碱金属硫酸盐时,其活性迅速增加,以FeCl_3 + Na_2 SO_4为最佳,是一种比较理想的催化剂,价格便宜,来源丰富;几种典型化合物或混合物或混合物的催化活性为FeCl_3 + Na_2 SO_4 > Na_2 CO_3、K_2 CO_3、K_2 CO_3 > Fe_3 O_4 + Na_2 SO_4 > NiCl_2 + Na_2 SO_4 > NiCl_2 > FeCl_3 + Na_2 CO_3 > Fe_3Cl_3 > CoCl_2;通过测定物相提出了单一化合物的催化机理。CO_2 + FeO → CO + Fe_2 O_3 F_2 O_3 + C → FeO + CO FeCl_3 + Na_2 SO_4复合催化剂的催化机理:铁主要起传递氧的作用,而Na对Fe的扩散起促进作用,同时也有少量Na参与氧的传递C + Fe_2 O_3 → FeO + CO C + Na_2 O → Na + CO FeO + CO_2 → Fe_2O_3 + CO Na + CO_2 → Na_2 O + CO Boudouard催化气化反应基本上符合兰格纪念尔吸附方程;由于活化能与指前因子具有补偿作用:LOG(A) = 0.18ΔE-2.30,不能单独将活化能或指前因子作为催化剂活性的判据,而必须根据Aexp(-ΔE/RT)来判断催化剂的催化活性。

Other Abstract

This paper based on the research works of predecessors has investigated systematically the influence of a variety of iron compounds and compound mixtures on the gasification rate of Boundouard reaction. This study deals with the effect of reaction conditions on the activity, catalytic reaction mechanism, kinetic parameters, etc. The results indicate the following: 1 Iron compound can enhance the gasification rate of carbon by carbon dioxide, but its activity is much lower than Na_2 CO_2、 K_2 CO_3. 2 The catalytic activity of iron compound is dependent upon the mixing way. i.e.: absorbed > impregnated > dry mixed. 3 The difference of catalytic activity of iron compounds is small during mixtures with iron in excess of 0.01wt. pct. 4 The anions in iron impregnated method, but do affect its catalytic activity in the wet impregnated method, but do affect its catalytic activity in the dry mixed method. The catalytic activity order is FeCL_3 >> FeCl_2 > F_2 O_3 > Fe > Fe_2 (SO_4)_3 > FeSO_4. 5. Catalytic activity order of some typical compounds or compound mixtures is FeCl_3 + Na_2 SO_4 > Na_2 CO_3、K_2 CO_3 > Fe_3 O_4 + Na_2 SO_4 > NiCl_2 + Na_2 SO_4 > NiCl_2 > FeCl_3 + Na_2 SO_4 > Na_2 CO_3 > Na_2SO_4 > FeCl_3 > CoCl_2 6. 5wt%Fe(FeCl_3) + 5wt%Na(Na_2SO_4) is an ideal catalyst which price is very low. 7. The catalytic mechanisms deduced from XPD parameters would be represented by Eqs. (1) and (2) for simple iron compound: CO_2 + FeO → CO + Fe_2O_3 (1) C + Fe_2O_3 → CO + FeO (2) where iron is regarded as an oxygen carrier by an oxidation-reduction cycle. There are Egs (3) to (6) for mixture of iron compound and sodium salt:C + Na_2 O → Na + CO (3) C + Fe_2 O_2 → FeO + CO (4) FeO + CO_2 → Fe_2 O_3 + CO (5) Na + CO_2 → Na_2 O + CO (6) It is recognized that iron plays an essential role of transmitting oxygen, whereas sodium promotes iron activity, and transmitts a little oxygen. 8. The reaction of catalystic gasification is in agreement with Langmuir-Hinshchwood equation(7) Rate = (K_1 Pco_2)/(1 + K_2 Pco_2 + K_3 Pco) (7) 9. Kinetic study has shown that activition energies(ΔE) have a compensation relation with the pre-exponents(A). They have been correlated by Eq.(8) LogA = 0.18ΔE - 2.30 (8).

Document Type学位论文
Recommended Citation
GB/T 7714
赵连权. 铁化合物对C + CO_2 <-> 2CO反应的催化作用[D]. 中国科学院研究生院,1989.
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