沼氣為有機物質經微生物厭氧消化之產物，其主成分為甲烷、二氧化碳、水氣及微量之硫化氫及氨，可做為燃料產生能量。然而其含有二氧化碳降低發熱值，且硫化氫為腐蝕性氣體可造成管線及鍋爐損壞。轉化沼氣為合成氣同時去除硫化氫可提升其發熱值及燃燒系統之穩定性。目前可行之沼氣轉化技術包括觸媒重組、光觸媒重組及非熱電漿重組，但是這些技術皆有其發展限制。結合光觸媒與非熱電漿為一複合反應器可引致電漿與光觸媒間之交互作用，進而改善兩技術之缺點，提升沼氣重組效率。本研究開發非熱電漿反應器進行沼氣重組產生合成氣，並製備LaFeO3 (LFO)、Ag-LaFeO3 (ALFO)及Ag-LaFeO3/TiO2 (ALFTO)光觸媒分別填入電漿反應器以探討對合成氣生成效率之影響。實驗結果顯示未填入光觸媒之電漿反應器在不含硫化氫之沼氣流率為350 mL/min時有較高之合成氣能量效率(14.5 mol/kWh)，填入ALFTO光觸媒可進一步提升至20.2 mol/kWh。通入硫化氫後合成氣之能量效率分別下降至13.4及17.4 mol/kWh，含硫副產物之生成也降低電漿光觸媒系統可穩定操作之時間。加入BaTa0.3Nb0.7O3 (BTaNO)光觸媒雖降低合成氣之產率，但可轉化含硫副產物進而提升重組系統對硫化氫之抵抗性。協同測試結果指出光觸媒具有熱催化及光催化特性，且複合反應器之合成氣能量效率高於電漿、熱催化及光催化之能量效率總和，顯示複合反應氣存在協同作用。光觸媒之物化特性分析指出電漿及光觸媒之間存在良好之交互作用，電漿可改變光觸媒之表面結構，光觸媒亦可增加反應速率及提供多反應途徑。最後，TGA分析結果指出添加BTaNO可減少含硫副產物之生成進而增加反應系統穩定操作時間。;Biogas comes from the anaerobic digestion of organics and is composed of methane, carbon dioxide, water vapor and trace amount of hydrogen sulfide and ammonia. Biogas can serve as a fuel to generate energy, nevertheless, carbon dioxide reduces its heating value while H2S is corrosive to pipeline and boiler. Converting biogas into syngas and removing H2S can increase its heating value and the stability of combustion system. So far, available biogas reforming technologies include catalysis, photocatalysis and nonthermal plasma, but all of these methodologies have shortcomings for field application. Further combination of photocatalyst with nonthermal plasma into a hybrid reactor can induce interactions between plasma and photocatalyst to solve the bottlenecks and to enhance biogas reforming efficiency. In this study we developed a nonthermal plasma reactor to reform biogas into syngas, and prepared LaFeO3 (LFO), Ag-LaFeO3 (ALFO) and Ag-LaFeO3/TiO2 (ALFTO) to pack into plasma reactor individually to explore their influence on syngas generation rate. Results show that energy efficiency achieved with plasma reactor without photocatalyst and H2S is 14.5 mol/kWh, which is further increased to 20.2 mol/kWh as ALFTO photocatalyst is integrated to form the hybrid system. Introducing H2S reduces energy efficiency to 13.4 and 17.4 mol/kWh, respectively, and shorten the stable operation period of photocatalysis reactor. The effect of H2S can be reduced by adding BaTa0.3Nb0.7O3 (BTaNO) photocatalyst even though the energy efficiency is reduced. Synergy test results indicate that photocatalysts applied have catalytic and photocatalytic activities. In addition, the energy efficiency achieved with the hybrid reactor is higher than the summation of plasma-alone, catalysis and photocatalysis reactors, implying the existence of synergistic effects. Characterization of photocatalysts reveals good interactions between plasma and photocatalyst including plasma improves surface structure and photocatalyst enhances reaction rate and provides multi-reaction routes. Finally, TGA analysis result pointed out that addition of BTaNO reduces generation rate of sulfur-containing byproducts and further stabilize reforming system operation.
