Ishihara Atsushi, Kanamori Shouhei, Hashimoto Tadanori
Division of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurima Machiya-Cho, Tsu, Mie 514-8507, Japan.
ACS Omega. 2021 Feb 18;6(8):5509-5517. doi: 10.1021/acsomega.0c05855. eCollection 2021 Mar 2.
Zn-exchanged ZSM-5-AlO (ZA) composite-supported Pt/NiMo (NM) sulfided catalysts were prepared using the conventional kneading method and were tested for dehydrocyclization-cracking of soybean oil. The effects of Zn addition on the activity and selectivity of products were investigated under moderate-pressure conditions of 0.5 and 1.0 MPa H in the temperature range of 420-580 °C. At the temperature 500 °C and higher, most of the sample soybean oil was converted at both the pressures of 0.5 and 1.0 MPa. At 1.0 MPa and 500 °C, the effects of Zn addition appeared and increased the yields of aromatics, while the catalyst without Zn produced larger amounts of products with more than C18. Further, at 0.5 MPa and 580 °C, the gas formation was inhibited in comparison to the cases of 1.0 MPa and the effects of the Zn addition also appeared and increased the yields of aromatics, while the catalyst without Zn produced larger amounts of products with more than C18. The Pt/NM/Zn(122)ZA test catalyst produced more than 63% of liquid fuels in the range C5-C18, and the yield of aromatics was 13%, the maximum value in the present study. The following reaction routes were proposed. The structure of triglyceride is converted by hydrocracking to three molecules of aliphatic acids and propane on the surface PtNiMo sulfide on AlO support. The converted aliphatic acids are decomposed through decarboxylation to hydrocarbon fragments, which are further decomposed by cracking on the acid sites of the catalyst, the surface of NiMo sulfide, AlO, or ZSM-5. Finally, the formed C3 and C4 olefins are transformed to aromatics through the Diels-Alder reaction on the Zn species of ZnZSM-5. On the other hand, although gases were relatively small in amount, aromatic compounds were formed significantly, suggesting that cyclization might directly occur without conversion to gaseous hydrocarbons to some extent.
采用传统捏合方法制备了锌交换ZSM-5-AlO（ZA）复合载体负载的Pt/NiMo（NM）硫化催化剂，并对其进行了大豆油脱氢环化裂解测试。在420-580℃温度范围内，在0.5和1.0MPa氢气的中压条件下，研究了锌添加量对产物活性和选择性的影响。在500℃及更高温度下，大部分样品大豆油在0.5和1.0MPa压力下均发生了转化。在1.0MPa和500℃时，锌添加的影响显现出来，提高了芳烃产率，而不含锌的催化剂则产生了大量碳数超过C18的产物。此外，在0.5MPa和580℃时，与1.0MPa的情况相比，气体生成受到抑制，锌添加的影响也显现出来，提高了芳烃产率，而不含锌的催化剂则产生了大量碳数超过C18的产物。Pt/NM/Zn(122)ZA测试催化剂在C5-C18范围内产生了超过63%的液体燃料，芳烃产率为13%，是本研究中的最大值。提出了以下反应路线。甘油三酯的结构通过加氢裂化在AlO载体上的表面PtNiMo硫化物上转化为三分子脂肪酸和丙烷。转化后的脂肪酸通过脱羧分解为烃片段，这些烃片段在催化剂的酸性位点、NiMo硫化物表面、AlO或ZSM-5上进一步通过裂化分解。最后，生成的C3和C4烯烃通过在ZnZSM-5的锌物种上的狄尔斯-阿尔德反应转化为芳烃。另一方面，尽管气体量相对较小，但芳烃化合物显著形成，这表明在一定程度上可能直接发生环化而无需转化为气态烃。
