KOH连续活化法由石油焦制备高比表面积活性炭的关键科学问题

This work is to develop the theoretical and technical framework up which high specific surface area activated carbons are continuously prepared from petroleum coke with KOH as activation agent. The preparation process should be conducted efficiently with high throughput and low consume of KOH and, in addition, be safe and environment-friendly. For this purpose, a screw type carbonization reactor and a vertical activation furnace have been set up to carry out the pretreatment (carbonization/dehydration) of petroleum coke/KOH and the activation of the pretreated sample, respectively. Based on the above-mentioned reactors and a horizontal pipe reactor, together with conventional and modern analytical tools, effects of the type of raw material, reactor temperature profile, residence time of the sample, and reaction atmosphere on the activation process and the property of the activated carbons are going to be systematically investigated. The research focuses lie in: the law of petroleum coke activation with KOH under H2 atmosphere, the formation and intercalation of K into the interlayer space of the graphite crystallite of carbons, especially that enhanced by H2 addition during the activation, and the deintercalation of K with agents of varied properties, such as H2O, NH3, H2S. As a result,the activation mechanism could be further elucidated following the fingerprints of the reactions, i.e. the chemical composition, surface property and nanotexture of the carbons. And a new way to concisely control the porous and surface property of the activated carbons and also to produce some specialized heteroatom-doped carbon materials could be established.

构建KOH 连续活化法由石油焦制备高比表面积活性炭的理论和技术体系。分别采用螺杆式炭化反应器和立式活化反应器进行石油焦/KOH的预处理（炭化/脱水）和预处理样品的活化。以上述反应器和水平管式反应器为实验平台，结合常规和现代仪器分析手段，系统研究原料和炭前躯体性质以及典型工艺条件（反应器温度分布、物料停留时间、反应气氛等）对活化过程和产品性质的影响规律。重点研究：H2气氛对KOH活化石油焦的影响机制；K对构成炭的石墨微晶的插层、特别是活化过程H2对K生成和插层的强化，以及不同试剂（例如H2O，NH3，H2S等）对K的脱插规律。依据活化反应过程炭的化学组成、表面性质和纳米织构的变化，进一步阐明KOH活化石油焦的机理。实现对活性炭表面性质和孔隙结构的可控调变，同时探索利用K的脱插制备功能性掺杂炭材料的新途径。为高比表面积活性炭的高效、低耗、安全、环境友好和规模化可控制备与应用提供理论与技术支撑。

传统间歇式KOH活化法由石油焦制备高比表面积活性炭过程具有碱耗高、产品性能调控困难、生产效率低和存在安全隐患等问题。针对上述问题，利用管式炉反应器研究了KOH活化石油焦制备高比表面积活性炭过程中各种产物的产生机制，结果表明，活化过程中产生的钾可以插层到活性炭的碳网层片中，促进其孔隙结构的发展。基于KOH活化过程中产生单质钾及其对石墨微晶碳网层片的插层现象，利用插层钾的高反应活性，通过分子探针反应，建立了活化过程中插层钾的定量表达方法；提出通过插层钾的脱插，实现产品活性炭孔结构和表面性质调控的策略。系统考察了不同温度下、不同浓度的含氧试剂（水、醋酸、甲醇、乙醇等）、NH3和H2S对插层钾的脱插行为，及其对产品活性炭孔隙结构和表面性质的影响规律。利用低温氮吸附测定了活性炭的吸、脱附等温线，考察了脱插对活性炭孔隙结构的影响；通过Boehm滴定分析、元素分析、红外分析等考察了脱插对活性炭表面性质的影响；通过XPS分析、XRD分析及Gibbs自由能计算，构建了活化过程钾插层及脱插的机理模型。.针对KOH活化过程中由于KOH熔融导致物料黏壁，并因此难以连续生产的弊端，设计建设了转炉反应器，并在此反应器中对石油焦的低温碱活化过程及其影响因素进行了系统研究。探究在活化反应过程中KOH、K、K2O、K2CO3等的变化规律，以及反应工艺条件（温度、碱焦比、转速、滚珠构成、反应气氛等）对物料黏壁现象消除及活性炭产品性能的影响机制；确定了消除黏壁现象的适宜工艺条件，同时阐明炉内滚珠消除黏壁现象的作用原理。形成了以转炉反应器为主体的连续KOH活化法制备高比表面积活性炭工艺。.上述工作为高比表面积活性炭的高效、低耗、安全、环境友好和规模化可控制备与应用提供了理论与技术支撑。