Unraveling combustion chemistry of dimethyldiethoxysilane. I. A comprehensive pyrolysis investigation with insight into ethanol formation mechanism in combustion of ethoxysilane flame synthesis precursors

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2024-10-17 DOI:10.1016/j.combustflame.2024.113794

Qilong Fang , Jun Fang , Wei Li , Tianyou Lian , Long Zhao , Wang Li , Lili Ye , Yuyang Li

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引用次数: 0

Abstract

Ethoxysilanes are a family of precursors widely used in flame synthesis of silica nanoparticles. The existence of a silicon atom greatly amplifies the complexity of ethoxysilane combustion reactions, especially the detection of silicon-containing products and exploration of the specific reaction pathways, which hinders the unambiguous understanding of the combustion chemistry of ethoxysilanes. As the first part of a serial work on the combustion of dimethyldiethoxysilane (DMDEOS), a representative ethoxysilane precursor, reports a theoretical, experimental, and kinetic modeling investigation on its pyrolysis. The potential energy surface and rate constants show that the four-membered ethylene elimination dominates the decomposition of DMDEOS. Pyrolysis products in the micro-flow reactor pyrolysis of DMDEOS are detected using synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS), including six silicon-containing products and an abundant of hydrocarbon molecules and radicals. Novel insight is provided into the unclear ethanol formation mechanism in previous pyrolysis investigations of ethoxysilanes. Previously proposed one-step mechanisms are found to be less efficient based on theoretical exploration and experimental evidence. A new multi-step mechanism initiated from the ethanol elimination of HOSi(CH₃)₂OC₂H₅ is concluded to be energy-favorable, which is supported by the identification of relevant products in the micro-flow reactor pyrolysis experiment. Based on the product information detected by SVUV-PIMS and the exploration of ethanol formation mechanism, a kinetic model of DMDEOS pyrolysis is constructed and validated against the new data that flow reactor pyrolysis of DMDEOS at 1.05 atm and 849–1113 K using gas chromatography. The model can effectively reproduce the formation of observed products and successfully address the substantial underprediction of ethanol caused by previously proposed one-step mechanisms. Modeling analyses, including rate of production analysis and sensitivity analysis, are performed to provide insight into the key pathways of DMDEOS decomposition and product formation.

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揭开二甲基二乙氧基硅烷燃烧化学的神秘面纱。I. 全面热解研究，深入了解乙氧基硅烷火焰合成前体燃烧中乙醇的形成机理

乙氧基硅烷是广泛用于火焰合成纳米二氧化硅的前驱体家族。硅原子的存在大大增加了乙氧基硅烷燃烧反应的复杂性，尤其是含硅产物的检测和具体反应途径的探索，阻碍了对乙氧基硅烷燃烧化学的明确认识。作为乙氧基硅烷代表性前体二甲基二乙氧基硅烷（DMDEOS）燃烧系列研究的第一部分，报告了对其热解的理论、实验和动力学模型研究。势能面和速率常数表明，四元乙烯消解在 DMDEOS 的分解过程中占主导地位。利用同步辐射真空紫外光离子化质谱（SVUV-PIMS）检测了微流反应器热解 DMDEOS 的热解产物，包括六种含硅产物和丰富的碳氢化合物分子及自由基。该研究对以往乙氧基硅烷热解研究中不明确的乙醇形成机理提出了新的见解。根据理论探索和实验证据，发现以前提出的一步机制效率较低。由 HOSi(CH3)2OC2H5 的乙醇消除引发的新的多步骤机制被认为是能量有利的，微流反应器热解实验中相关产物的鉴定也支持了这一观点。根据 SVUV-PIMS 检测到的产物信息和对乙醇形成机理的探索，构建了 DMDEOS 热解动力学模型，并利用气相色谱法对 1.05 atm 和 849-1113 K 条件下流动反应器热解 DMDEOS 的新数据进行了验证。该模型可以有效地再现观察到的产物的形成，并成功地解决了之前提出的单步机制导致的乙醇大量预测不足的问题。模型分析（包括生成率分析和敏感性分析）有助于深入了解 DMDEOS 分解和产物形成的关键途径。

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.