The balance between metal and acid sites directly affects the preparation of high-performance cracking catalysts with high heat sink and low coking.Nevertheless,how to control acid-metal sites balance and its relation...The balance between metal and acid sites directly affects the preparation of high-performance cracking catalysts with high heat sink and low coking.Nevertheless,how to control acid-metal sites balance and its relationship with cracking performance are reported scarcely.In this work,a series of Pt/Al_(2)O_(3)-SiO_(2) dual sites catalysts with different metal to acid active sites ratio(C_(M)/C_(SA))were constructed by ethanolassisted impregnation method and the impact on n-decane cracking under supercritical conditions was systematically and deeply investigated.The results showed that the conversion and carbon deposition increased gradually with varied C_(M)/C_(SA)and reached the balance at C_(M)/C_(SA)of 0.13.The proper ratio C_(M)/C_(SA)(0.13)can balance the deep dehydrogenation coking over metal active sites and high heat sink of cracking over acid active sites,the chemical heat sink reaches amazing 1.75 MJ/kg and carbon deposition is only22.03 mg/cm^(2) at 750℃.Meanwhile,the few metal sites at low C_(M)/C_(SA)and the few strong acid sites at high C_(M)/C_(SA)are the main factors limiting the cracking activity.Low C_(M)/C_(SA)limit the activation of C-H bond and deep dehydrogenation of coking precursor,resulting in relative low cracking activity and carbon deposition,while high C_(M)/C_(SA)limit the activation of C-C bond and increase the deep dehydrogenation.In this contribution,design and construction of metal-acid dual sites can not only provide the technical solution for the preparation of high heat sink and low coking cracking catalyst,but also deepen the understanding of the cracking path of hydrocarbon fuel.展开更多
这是一篇矿山生态修复领域的论文。矿山开发过程中不可避免产生大量废石,废石中重金属元素在风化、淋溶等作用下释放,将对矿区周边水土环境质量产生影响。为了研究某铅锌矿废石重金属元素淋溶规律,分析了该废石的化学组成和产酸潜力。...这是一篇矿山生态修复领域的论文。矿山开发过程中不可避免产生大量废石,废石中重金属元素在风化、淋溶等作用下释放,将对矿区周边水土环境质量产生影响。为了研究某铅锌矿废石重金属元素淋溶规律,分析了该废石的化学组成和产酸潜力。模拟强酸雨环境下,分析了废石中重金属元素溶出率及淋溶前后废石的矿物组成。结果表明:该废石中重金属Cu、Pb、Zn、Cd、As元素无独立矿物,在废石中分散赋存;废石酸中和能力较高,净产酸量NAG为0 kg H_(2)SO_(4)/t,无产酸潜力。在模拟强酸雨淋溶实验中,淋出液pH值均呈弱碱性,这与废石含较多的碱性矿物有关,废石具有一定的酸缓冲能力;第1轮淋溶过程Cu、Pb、Zn、Cd、As元素随淋溶时间延长累积溶出率逐渐升高;第2轮淋溶2周期后Cu、Pb、Zn、Cd元素累积溶出率趋于稳定,后续基本不溶出;As元素累积溶出率随淋溶时间延长而升高;总体而言,废石中重金属溶出率低。废石淋溶前后矿物成分不变,矿物含量略有变化。本文可为矿山废石堆场管理及其周边重金属污染防治提供依据。展开更多
基金subsidized by Sichuan Province Science and Technology Program (2023NSFSC0093)Enterprises Entrust Technology Development Program (FJF22KX0055,202302914)。
文摘The balance between metal and acid sites directly affects the preparation of high-performance cracking catalysts with high heat sink and low coking.Nevertheless,how to control acid-metal sites balance and its relationship with cracking performance are reported scarcely.In this work,a series of Pt/Al_(2)O_(3)-SiO_(2) dual sites catalysts with different metal to acid active sites ratio(C_(M)/C_(SA))were constructed by ethanolassisted impregnation method and the impact on n-decane cracking under supercritical conditions was systematically and deeply investigated.The results showed that the conversion and carbon deposition increased gradually with varied C_(M)/C_(SA)and reached the balance at C_(M)/C_(SA)of 0.13.The proper ratio C_(M)/C_(SA)(0.13)can balance the deep dehydrogenation coking over metal active sites and high heat sink of cracking over acid active sites,the chemical heat sink reaches amazing 1.75 MJ/kg and carbon deposition is only22.03 mg/cm^(2) at 750℃.Meanwhile,the few metal sites at low C_(M)/C_(SA)and the few strong acid sites at high C_(M)/C_(SA)are the main factors limiting the cracking activity.Low C_(M)/C_(SA)limit the activation of C-H bond and deep dehydrogenation of coking precursor,resulting in relative low cracking activity and carbon deposition,while high C_(M)/C_(SA)limit the activation of C-C bond and increase the deep dehydrogenation.In this contribution,design and construction of metal-acid dual sites can not only provide the technical solution for the preparation of high heat sink and low coking cracking catalyst,but also deepen the understanding of the cracking path of hydrocarbon fuel.
文摘这是一篇矿山生态修复领域的论文。矿山开发过程中不可避免产生大量废石,废石中重金属元素在风化、淋溶等作用下释放,将对矿区周边水土环境质量产生影响。为了研究某铅锌矿废石重金属元素淋溶规律,分析了该废石的化学组成和产酸潜力。模拟强酸雨环境下,分析了废石中重金属元素溶出率及淋溶前后废石的矿物组成。结果表明:该废石中重金属Cu、Pb、Zn、Cd、As元素无独立矿物,在废石中分散赋存;废石酸中和能力较高,净产酸量NAG为0 kg H_(2)SO_(4)/t,无产酸潜力。在模拟强酸雨淋溶实验中,淋出液pH值均呈弱碱性,这与废石含较多的碱性矿物有关,废石具有一定的酸缓冲能力;第1轮淋溶过程Cu、Pb、Zn、Cd、As元素随淋溶时间延长累积溶出率逐渐升高;第2轮淋溶2周期后Cu、Pb、Zn、Cd元素累积溶出率趋于稳定,后续基本不溶出;As元素累积溶出率随淋溶时间延长而升高;总体而言,废石中重金属溶出率低。废石淋溶前后矿物成分不变,矿物含量略有变化。本文可为矿山废石堆场管理及其周边重金属污染防治提供依据。
