CO₂作为最主要的温室气体之一，其大量排放导致一系列气候问题，将CO₂定向转化为CO，可实现CO₂高附加值利用。低温等离子体因其能将CO₂转化为高附加值化合物而受到广泛关注。因此，本研究利用介质阻挡放电等离子体(DBD)在常温常压下转化CO₂，探究了工艺参数和反应器参数对CO₂转化效率的影响。基于此，进一步在反应器中填充泡沫金属、ZnO以及ZnO-ZrO₂复合催化剂，以提高CO₂转化效率。主要研究内容及结果如下：

(1) 探究了单一介质阻挡放电等离子体转化CO₂。通过改变放电功率、停留时间、CO₂浓度等工艺参数以及外电极长度、内电极材料、放电间隙等反应器参数进行CO₂转化。研究发现，工艺参数和反应器参数均对CO₂转化起着重要作用。随着放电功率的增加和停留时间的延长，CO₂转化率均增大。当CO₂浓度为20%时，CO₂转化率达到最佳。当放电功率和停留时间保持不变，内电极材料为不锈钢棒时，在外电极长度为16 cm和放电间隙为1.0 mm的反应器中，CO₂转化率最佳。

(2) 为解决单一DBD反应器中CO₂转化率难以提升的问题，将一元或二元泡沫金属(Ni、Fe和Cu)填充至反应器中，探究其对CO₂转化的影响。研究发现，泡沫金属的填充对反应有显著影响。在一元泡沫金属中，泡沫铁与DBD的协同催化转化效果最好，最高可达到30.1%，填充泡沫镍的CO₂转化率最高可达25.5%，而填充泡沫铜的CO₂转化率仅为17.8%。在相同的测试条件下，将铁镍二元泡沫金属填充至DBD反应器中，结果表明当铁和镍的比例为7：3时，可同时具有较高的CO₂转化效率和最佳的稳定性能。

(3) 由于泡沫金属的高导电性，导致在反应器中出现明显局部放电现象，且块状泡沫金属填充过程容易损坏反应器。为解决这一问题，进一步选用金属氧化物作为催化剂，通过化学沉淀法制备出ZnO，并探究其对CO₂转化效率的影响。研究发现，在填充自制ZnO的反应器中，CO₂转化率和能量效率均高于空管反应器，且转化率最高可达29.8%，能量效率最高可到1.9%。当改变ZnO填充量和停留时间时，CO₂转化率在较长停留时间和0.2 g填充量的条件下最高。进一步测试自制ZnO的稳定性，结果表明，自制ZnO在高功率下容易失活，达到稳定后，CO₂转化率仅为23%左右。但失活ZnO经过DBD处理后，其再生后的催化能力可达到新制催化剂的95%以上。此外，将商业ZnO与自制ZnO进行对比，结果发现商业ZnO的CO₂转化效率为26.7%，表明自制ZnO具有更高的转化效率。经物理表征发现，自制ZnO具有更高的比表面积和氧空位，为CO₂转化提供更多活性位点，从而提高CO₂转化效果。

(4) 为解决ZnO在高放电功率下稳定性较差的问题，引入了ZrO₂。采用共沉淀法制备了ZnO-ZrO₂复合催化剂，以提高ZnO的稳定性。研究发现，填充ZnO-ZrO₂(7:3)催化剂能显著提升CO₂转化。在高放电功率下，ZnO-ZrO₂(7:3)催化剂能在较长时间内保持很高的CO₂转化率，最高可达33.3%，达到稳定后CO₂转化率也可达29%。对催化性能最佳的ZnO-ZrO₂(7:3)催化剂进行物理表征发现，ZnO-ZrO₂(7:3)具有较高的比表面积和活性位点，且在复合催化剂中存在界面效应，不仅有助于提高ZnO稳定性，还有利于CO₂转化。

As one of the most important greenhouse gases, CO₂ emissions lead to a series of climate problems. The directional conversion of CO₂ into CO can realize high value-added utilization of CO₂. Low temperature plasmas have attracted much attention because of their ability to convert CO₂ into high value-added compounds. Therefore, in this study, dielectric barrier discharge plasma (DBD) was used to convert CO₂ at normal temperature and pressure, and the influence of process parameters and reactor parameters on CO₂ conversion efficiency was investigated. Based on this, the reactor was further filled with foam metal, ZnO and ZnO-ZrO₂ composite catalysts to improve the CO₂ conversion efficiency. The main research contents and results are as follows:

(1) The conversion of CO₂ by single dielectric barrier discharge plasma was investigated. The CO₂ conversion was carried out by changing the process parameters such as discharge power, residence time, CO₂ concentration, outer electrode length, inner electrode material, discharge gap and other reactor parameters. It is found that both process parameters and reactor parameters play an important role in CO₂ conversion. With the increase of discharge power and the extension of residence time, the CO₂ conversion rate increases. When the concentration of CO₂ is 20%, the conversion rate of CO₂ reaches the optimum. When the discharge power and residence time remain unchanged and the inner electrode material is stainless steel rod, the reactor with the outer electrode length of 16 cm and discharge gap of 1.0 mm has the best CO₂ conversion rate.

(2) In order to solve the problem that it is difficult to increase the CO₂ conversion rate in a single DBD reactor, singular or binary foam metals (Ni, Fe and Cu) were filled into the reactor to explore its influence on CO₂ conversion. It was found that the filling of foam metal had a significant effect on the reaction. Among the singular foam metals, the synergistic catalytic conversion effect of iron foam and DBD is the best, and the CO₂ conversion rate of nickel foam is up to 25.5%, while the CO₂ conversion rate of copper foam is only 17.8%. Under the same test conditions, Fe-Ni binary foam metal was filled into DBD reactor, and the results showed that when the ratio of iron to nickel was 7:3, both high CO₂ conversion efficiency and the best stability performance could be achieved simultaneously.

(3) Due to the high electrical conductivity of the metal foam, there is obvious partial discharge in the reactor, and the bulk metal foam filling process is easy to damage the reactor. To solve this problem, ZnO was prepared by chemical precipitation using metal oxide as catalyst, and its effect on CO₂ conversion efficiency was investigated. It is found that the CO₂ conversion and energy efficiency of the reactor filled with self-made ZnO are higher than that of the empty tube reactor, and the conversion rate is up to 29.8%, and the energy efficiency is up to 1.9%. When the ZnO filling amount and residence time were changed, the CO₂ conversion rate was the highest under the condition of longer residence time and 0.2 g filling amount. Further testing of the stability of self-made ZnO shows that the self-made ZnO is easy to be deactivated at high power, and the CO₂ conversion rate is only about 23% after reaching stability. However, the catalytic capacity of deactivated ZnO after DBD treatment can reach more than 95% of the new catalyst. In addition, comparing commercial ZnO with homemade ZnO, it is found that the CO₂ conversion efficiency of commercial ZnO was 26.7%, indicating that self-made ZnO has a higher conversion efficiency. Through physical characterization, it is found that self-made ZnO has higher specific surface area and oxygen vacancy, which provides more active sites for CO₂ conversion, thus improving the CO₂ conversion effect.

(4) In order to solve the problem of poor stability of ZnO at high discharge power, ZrO₂ is introduced. The ZnO-ZrO₂ composite catalyst was prepared by coprecipitation method to improve the stability of ZnO. It is found that filling ZnO-ZrO₂(7:3) catalyst can significantly improve CO₂ conversion. At high discharge power, the ZnO-ZrO₂(7:3) catalyst can maintain a high CO₂ conversion rate for a long time, up to 33.3%, and the CO₂ conversion rate can also reach 29% after stability. Physical characterization of ZnO-ZrO₂(7:3) with the best catalytic performance shows that ZnO-ZrO₂(7:3) has a high specific surface area and active site, and there is an interfacial effect in the composite catalyst, which not only enhances the stability of ZnO but also facilitates the conversion of CO₂.