由苯與乙烯生產乙苯：程序設計及優化、技術經濟分析與生命週期評估

Abstract

本研究針對乙苯(EB)製程建立一套整合製程設計、技術經濟分析(TEA)與生命週期評估(LCA)的系統化評估框架，系統性探討該製程於技術、經濟與環境層面之整體表現。EB製程為典型多單元整合系統，包含兩座反應器、兩座蒸餾塔及兩段物料回收迴路，其關鍵特徵在於副產物二乙苯(DEB)之回收與再轉化策略。透過反應段之功能性配置，使主反應與副反應於不同反應器中分工進行，不僅提升EB選擇率，亦有效降低DEB生成量，並為後續分離單元之能耗降低與成本改善奠定基礎。 從TEA結果顯示，在內部報酬率(IRR)設定為15 %時，EB的最低銷售價格(MSP)為1.024USD/kg，與近年國際市場價格(0.70–1.20 USD/kg)相符，進一步分析指出，製程總成本主要由原料費用所主導，此一經濟熱點分布與LCA所識別之環境衝擊熱點呈現高度一致性，顯示經濟與環境績效具有共同的關鍵驅動因子。雖然整體表現主要受上游原料供應鏈所影響，製程內部之能源使用效率與公用設施配置仍提供具體可行的改善空間。 綜合分析結果顯示，EB製程之永續表現主要受上游原料來源、製程能源效率與公用設施架構三者共同主導。原料來源可引入低碳原料來源如生質乙烯、回收基苯可顯著降低環境衝擊，而透過熱整合與能效最佳化則能同步降低操作成本與能源消耗。進一步而言，若能源端導入低碳或再生能源，則可在不改變主製程配置的前提下，進一步提升整體永續性。本研究所建立之整合分析框架可作為未來化工製程規劃、綠色製程開發及永續投資決策之重要參考。

This study develops a comprehensive evaluation framework for ethylbenzene (EB) production by integrating process design, techno-economic analysis (TEA), and life cycle assessment (LCA), enabling a simultaneous assessment of technical feasibility, economic viability, and environmental sustainability. EB process represents a typical multi-unit integrated system, consisting of two reactors, two distillation columns, and two recycle loops. An unusual feature lies in the recovery of diethyl benzene (DEB), where functional allocation of the reaction network enables the main and side reactions to proceed in different reactors. This configuration enhances overall EB selectivity, suppresses DEB formation, and provides a favorable basis for reducing energy consumption and costs in separation units. TEA results indicate that, at an internal rate of return (IRR) of 15%, the minimum selling price (MSP) of EB is 1.024 USD/kg, falling within the international market range of 0.70–1.20 USD/kg. Further analysis shows that the total process cost is predominantly driven by raw material expenses. This economic hotspot distribution closely corresponds with the environmental impact hotspots identified by the LCA, indicating that the economic and environmental performance share common key drivers. Although the overall performance is primarily influenced by the upstream raw material supply chain, internal process energy efficiency and the configuration of utility systems still offer tangible opportunities for improvement. The integrated analysis demonstrates that the sustainability performance of the EB process is jointly governed by three factors: upstream raw material sources, process energy efficiency, and utility infrastructure. Introducing low-carbon feedstocks, such as bio-based ethylene or recycled benzene, can significantly reduce environmental impacts, while heat integration and energy optimization can simultaneously lower operating costs and energy consumption. Furthermore, the adoption of low-carbon or renewable energy at the utility level can further enhance overall sustainability without altering the main process configuration. The integrated evaluation framework established in this study provides a valuable reference for future chemical process planning, green process development, and sustainable investment decision-making.