CO_2预处理操作条件对Ni-Co双金属催化剂性能与结构的影响（英文）

Effect of CO_2 Pretreatment Operation Conditions on the Catalytic Performance and Structure of Ni-Co Bimetallic Catalyst

与传统H2预处理方法相比,新型H2+CO2预处理方法(HCD)能显著提升Ni-Co双金属催化剂的沼气重整活性及抗积碳性能.考察了HCD预处理操作条件对催化剂性能与结构的影响.较好的HCD预处理操作条件是在催化剂经H2处理之后,再用175-200 mL·min-1的原料气CH4/CO2(比例为0:10)在780-800℃下还原0.5-1h.在优化预处理操作条件下对催化剂进行了511 h的耐久性考察,并运用X射线衍射(XRD)、热重-差示扫描量热(TG-DSC)、透射电子显微镜(TEM)等手段对耐久性测试后的催化剂进行了表征.在511 h的稳定性实验内,CH4、CO2转化率,H2、CO选择性及H2/CO体积比分别高达96%、97%,98%、99%及0.98.催化剂在测试期间的平均积碳速率仅为0.2 mg·g-1·h-1.在该预处理操作参数下,催化剂拥有最好的综合性能和良好的耐久性.

The performance of the Ni-Co bimetal ic catalyst was significantly improved by a novel H2 and CO2 （HCD） pretreatment in the dry reforming of methane compared with traditional H2 pretreatment. The effects of the HCD pretreatment operating conditions, such as pretreatment time, temperature, gas feeding ratio, and gas flow rate, on the catalytic performance of Ni-Co bimetal ic catalyst were investigated. The optimal pretreatment time, temperature, gas feeding ratio （CH4/CO2）, and gas flow rate were 0.5-1 h, 780-800 ° C, 0：10, and 175-200 mL·min-1, respectively. Biogas was simulated with CH4 and CO2 in a volume ratio of 1 and without any other diluted gas. The catalyst was characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, and thermogravimetry （TG） coupled to differential scanning calorimetry （DSC）. In a 511 h stability test under the optimized operating conditions, the catalyst pretreated with both H2 and CO2 exhibited excellent stability. The average conversions of CH4 and CO2, selectivities for H2 and CO, and volume ratio of H2/CO were 96%, 97%, 98%, 99%, and 0.98, respectively. The average carbon deposition rate over the Ni-Co bimetal ic catalyst was only about 0.2 mg·g-1·h-1. The characterization results revealed that the sintering speed of the metal greatly decreased with testing time, and the metal particle wil not greatly sinter with further testing time. The amount of deposited carbon on the catalyst gradual y decreased and growth of filamentous carbon over the surface of the catalyst could be inhibited.＆amp;nbsp;Thereby, great catalytic activity and stability could be obtained during the dry reforming of methane reaction.