工艺条件对Ni/Al2O3和Ni/CeO2-Al2O3催化剂在甲烷自热重整制氢反应中催化性能的影响

采用共沉淀法制备γ-Al₂O₃载体和不同Ce添加量的CeO₂-Al₂O₃载体，然后用浸渍法制备Ni负载质量分数10%的Ni/γ-Al₂O₃和Ni/CeO₂-Al₂O₃催化剂。在固定床微反装置中考察了反应温度、原料气配比和CH₄空速等工艺条件对Ni/γ-Al₂O₃和Ni/Ce₃₀Al₇₀O_δ催化剂在甲烷自热重整制氢反应中催化性能的影响。结果表明，添加Ce的催化剂催化性能有较大提高，在Ni/Ce₃₀Al₇₀O_δ催化剂上，反应温度750 ℃时, CH₄转化率94.3％，与Ni/Al₂O₃催化剂相比，提高20％。Ni/γ-Al₂O₃和Ni/CeO₂-Al₂O₃催化剂的CH₄转化率均随反应温度的升高而增大。原料气中n(O₂)∶n(CH₄)和n(H₂O)∶n(CH₄)的增加均能提高各催化剂的CH₄转化率。但n(O₂)∶n(CH₄)和n(H₂O)∶n(CH₄)的变化对各催化剂的催化性能的影响不同。随着n(O₂)∶n(CH₄)的增大，产物中n（H₂）∶n（CO）降低，n（CO₂）∶n(CO＋CO₂)升高；而n(H₂O)∶n(CH₄)增大时，产物中n（H₂）∶n（CO）和n（CO₂）∶n(CO＋CO₂)均升高。随着CH₄空速的增加，Ni/Al₂O₃催化剂上CH₄转化率、n（H₂）∶n（CO）和n（CO₂）∶n(CO＋CO₂)均较大程度下降；而在Ni/Ce₃₀Al₇₀O_δ催化剂上，随着CH₄空速的增加，CH₄转化率、n（H₂）∶n（CO）和n(CO₂）∶n(CO＋CO₂)变化不大。

Effect of process conditions on performance of Ni/A12O3 and Ni/CeO2-A12O3 catalysts for autothermal reforming of methane

Supports of γ-Al₂O₃ and CeO₂-Al₂O₃ were prepared by co precipitation method and Ni/γ-Al₂O₃, Ni/CeO₂-Al₂O₃ catalysts with 10wt% Ni were prepared by impregnation method. The influence of reaction temperature, n(O₂)∶n(CH₄), n(H₂O)∶n(CH₄) and gas hourly space velocity(GHSV) of CH₄ on catalytic performance of Ni/γ-Al₂O₃ and Ni/Ce₃₀Al₇₀O_δcatalysts were studied in a fixed bed microreactor. The results show Ni/Ce₃₀Al₇₀O_δed that catalytic performance of the catalysts with addition of Ce were improved. The conversion of CH₄ was 94.3% at 750 ℃ over Ni/Ce₃₀Al₇₀O_δ catalyst.The results also showed that CH₄ conversion over Ni/γ-Al₂O₃and Ni/Ce₃₀Al₇₀O_δ catalysts increased with the rise of reaction temperature. The activities of all catalysts were improved with theincrease of n(O₂)∶n(CH₄)、n(H₂O)∶n(CH₄)and n(H₂O)∶n(CH₄).With the increase of n(O₂)∶n(CH₄)，H₂/CO molar ratio decreased and CO₂/(CO＋CO₂) molar ratio increased in products. Whereas the effects of n(H₂O)∶n(CH₄) on performance of Ni/Al₂O₃ and Ni/Ce₃₀Al₇₀O_δ catalysts were different. With the increaseof n(H₂O)∶n(CH₄)，n(H₂)∶n(CO) and n(CO₂)∶n(CO＋CO₂) all increased in products. With the increase in GHSV of CH₄ over Ni/γ-Al₂O₃ catalyst，methane conversion，n(H₂)∶n(CO) and n(CO₂)∶n(CO＋CO₂) were decreased obviously. With the increase in GHSV of CH₄ over Ni/Ce₃₀Al₇₀O_δ catalyst，however, methane conversion，n(H₂)∶n(CO) and n(CO₂)∶n(CO＋CO₂) had changed little.