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为了研究催化裂化、加氢等工艺过程中,硫醇类硫化物与固体酸性催化剂的B酸中心之间的相互作用机理,采用动力学和半经验量子力学方法,对几种典型硫醇类硫化物与H~+之间的相互作用进行了研究。以2-戊硫醇、环己硫醇和硫酚为模型化合物,模拟计算了各硫醇类硫化物的最高占据轨道(HOMO)以及H~+进攻硫位及不同碳位时所形成中间体的生成热及键长变化,进而讨论H~+的优先进攻位置以及反应中间体的稳定性。结果表明,H~+的进攻位置对形成的中间体的稳定性有很大影响。当H~+进攻硫醇类硫化物中的碳位时,反应中间体的生成热远大于或接近于H~+直接进攻硫位所形成的中间体的生成热;对于反应中间体的生成热同进攻硫位所形成的中间体的生成热相近的碳原子上的质子化反应,其实质与直接进攻硫原子时相一致,并生成硫化氢,这说明H~+将优先进攻硫醇类硫化物中的硫原子。由此可以认为,硫醇类硫化物在固体酸性催化剂的作用下,由于B酸中心的给质子性质,较容易在硫位上发生质子化反应,以生成硫化氢的形式转化脱除。
In order to study the interaction mechanism between mercaptan sulfides and B acid sites of solid acid catalysts in catalytic cracking and hydrogenation processes, several typical thiol sulfides Interaction between H ~ + and H ~ + was studied. Using 2-pentanethiol, cyclohexanethiol and thiophenol as model compounds, the highest occupied molecular orbital (HOMO) of each thiol sulfides and H + attacking sulfur and intermediates formed at different carbon positions were calculated Generate heat and bond length changes, and then discuss H ~ + priority attack position and the stability of the reaction intermediates. The results show that the attack position of H ~ + has great influence on the stability of the formed intermediates. When H ~ + attacks thiol sulfides in the carbon position, the reaction heat of formation of intermediates is far greater than or close to H ~ + direct attack on the formation of sulfur intermediates heat; for the reaction intermediates heat The protonation reaction on the carbon atom close to the heat of formation of the intermediate formed by attacking the sulfur site is essentially consistent with the direct attack on the sulfur atom and generates hydrogen sulfide, indicating that H ~ + will preferentially attack mercaptan sulfides Sulfur atoms in matter. Therefore, it can be considered that the mercaptan sulfides are more likely to undergo protonation at the sulfur sites due to the proton-donating nature of the B acid center under the action of a solid acidic catalyst, and the form of hydrogen sulfide is converted and removed.