- 學位論文
以甲醇為原料轉化為苯酚的產物選擇性控制之研究
Controlling the Product Selectivity in the Conversion of Methanol to the Feedstock for Phenol Production
摘要
這項研究提出了一種基於非石油的甲醇到苯酚的新式催化方法，其想法係將甲醇轉化為一混合物,其丙烯 與苯加甲苯 的莫耳比 = 1，而該混合產物可用於苯酚的製造。此外，該方法還將價值較低的副產物，如:間二甲苯、鄰二甲苯、九碳或九碳以上的重芳香烴和烷烴(甲烷、乙烷、丙烷和丁烷) ，轉化為高價值的產品，如對二甲苯及烯烴(乙烯、丙烯和丁烯)。 該研究探討了各種催化劑在條件為 0.1 MPa、430 °C下且空間速度為1.6 h-1 下的甲醇轉化率，使用的催化劑包含 HZSM-5、1wt% 的鋅添加至 HZSM-5 (1.0 wt% Zn/HZSM-5)、二氧化矽沉積於HZSM-5上 (Si/HZSM-5)、以及1.0 wt% Zn/Si/HZSM-5 和 1.5 wt% Zn/Si/HZSM-5 (分別為1.0 wt% Zn添加至Si/HZSM-5，和1.5 wt% Zn 添加至 Si/HZSM-5 )。 使用 HZSM-5 催化劑的主要產物為烷烴 (51.4wt％) 和芳香烴 (35.3wt％)。在芳香烴中，苯、甲苯和對二甲苯的組合選擇性僅佔19.3 wt％，其餘16.0 wt％ 用於價值較低的間二甲苯、鄰二甲苯和九碳或高於九碳以上的重芳香烴,而丙烯/苯加甲苯的莫耳比例僅有 0.2。 與 HZSM-5 性能相比, 1.0 wt％ 的Zn/HZSM-5的觸媒能烷烴轉變為芳香烴，而大部分轉化為間二甲苯、鄰二甲苯和九碳或九碳以上的高級芳香烴，致使對二甲苯、鄰二甲苯和二甲苯的總選擇性為 24.9 wt％，九碳或九碳以上的高級芳香烴，以及對苯、甲苯和對二甲苯的總選擇性為 23.6 wt％。而丙烯/苯加甲苯的莫耳比例依然維持在 0.2。 另外，與 HZSM-5 性能相比，Si/HZSM-5 將合併的苯，甲苯和對二甲苯的選擇性提高到29.4wt％，並降低烷烴的選擇性至 33.8 wt％。丙烯/苯加甲苯的莫耳比例提高至 0.8。因此，結合鋅的添加和二氧化矽的似乎存在一些加成作用。 添加 1.0 及 1.5 wt％ 的 Zn/Si/HZSM-5都顯示出烷烴大量轉化至烯烴及丙烯，且合併的苯、甲苯和對二甲苯的選擇性沒有太大變化。與 Si/HZSM-5 的性能相比，1.5 wt％ Zn/Si/HZSM-5 能維持苯、甲苯和對二甲苯選擇性在 30.5 wt% 下,進一步將烷烴的選擇性降低了至14.7 wt％，並且提高了烯烴的選擇性至 38.7 wt％。此種表現導致丙烯/苯加甲苯的莫耳比為 1.7，通過調整重空間速度將其進一步優化為接近1.0。 因此，於適當的條件下，在 ZSM-5 沸石上沉積二氧化矽及添加鋅，對於同時產出丙烯/苯加甲苯莫耳比=1及其高價值副產物相當重要。在本文中，研究了二氧化矽的沉積、鋅的添加、酸位點和製程操作條件等，對催化劑性能的影響，並分別進行了詳細地分析
並列摘要
This work proposed a novel nonpetroleum-based catalytic process of methanol to phenol. The idea was to convert methanol to produce a main product stream having a molar ratio of propylene to benzene, and toluene of unity. Such a product mix would be ideal for the manufacturing of phenol. In addition, the novel process suppressed lower-value byproducts including m-xylene, o-xylene, nine- or more-nine-carbon higher aromatics, alkanes (methane, ethane, propane, and butanes) and promoted higher value products such as para-xylenes and alkenes (ethylene, propylene, and butenes). The study investigated a series of catalysts including HZSM-5, 1 wt% Zn-impregnated HZSM-5 (1.0 wt% Zn/HZSM-5), silica-deposited HZSM-5 (Si/HZSM-5), as well as 1 wt% and 1.5 wt% Zn-impregnated silica-deposited HZSM-5 (1.0 wt% Zn/Si/HZSM-5 and 1.5 wt% Zn/Si/HZSM-5, respectively) for methanol conversion at 0.1 MPa, 430 °C and a weight hourly space velocity of 1.6 h-1. The HZSM-5 catalyst produced alkanes (51.4 wt%) and aromatics (35.3 wt%) as the main products. Amongst the aromatics, the desired combine selectivity of benzene, toluene, and p-xylene accounted for only 19.3 wt%, and the rest 16.0 wt% went to lower-valued m-xylene, o-xylene, and nine- or more-nine-carbon higher aromatics. The propylene to benzene and tolune molar ratio was only at 0.2. Compared to the performance of HZSM-5, 1.0 wt% Zn/HZSM-5 shifted alkanes to aromatics. A good fraction of the shifting, however, was directed toward m-xylene, o-xylene and nine- or more-nine-carbon higher aromatics, resulting in a combined selectivity of 24.9 wt% for m-xylene, o-xylene, and nine- or more-nine-carbon higher aromatics and a combined benzene, toluene and p-xylene selectivity of 23.6 wt%. The propylene to benzene and toluene molar ratio remained at 0.2. On the other hand, compared to the performance of HZSM-5, Si/HZSM-5 raised the combined benzene, toluene and p-xylene selectivity to 29.4 wt% and reduced the alkanes selectivity to 33.8 wt%. The propylene to benzene and toluene molar ratio moved up to 0.8. Thus, there appeared to be some synergies combining zinc impregnation and silica deposition. Both 1.0 wt% Zn/Si/HZSM-5 and 1.5 wt% Zn/Si/HZSM-5 showed a significant shifting of alkanes to alkenes and propylene, without much changes in the combined benzene toluene and p-xylene selectivity. Compared to the performance of Si/HZSM-5, 1.5 wt% Zn/Si/HZSM-5 further reduced alkanes selectivity to 14.7 wt%, raised alkenes selectivity to 38.7 wt%, and kept the combined benzene toluene and p-xylene selectivity at 30.5 wt%. Such a performance led to a propylene to benzene and toluene molar ratio of 1.7, which was further optimized to near 1.0 through the adjustment of weight hourly space velocity. Silica deposition and zinc impregnation on a ZSM-5 zeolite at proper process conditions appeared to be essential for generating a product stream having a propylene to benzene and toluene molar ratio of unity for methanol to phenol along with high-value by-products. A detailed analysis of the effects of silica deposition, zinc impregnation, acid sites and process conditions on the catalyst performance is presented.