Optimized adsorption processes for CO2 capture

工业烟气碳捕集与封存（CCS）技术被加拿大政府确定为减少CO2排放的重要技术。例如，一个500兆瓦的燃煤电厂生产约。每天排放16,000吨二氧化碳。从稀释的烟道气流（CO2组成为12 - 15%）中捕获CO2并将其浓缩至高纯度（> 90%），使用现有技术，例如，基于胺的吸收是昂贵的，并且需要开发替代品。使用固体吸附剂的吸附已被确定为一种有前途的选择。吸附式CO2捕集的主要挑战是：1.开发新型吸附剂; 2.设计和优化新的工艺配置（循环），以实现纯度和回收率> 90%的监管目标;以及3.实验示范（使用湿烟气）和成本估算，以与其他技术进行比较。本提案为挑战1开发了使能工具，为挑战2和挑战3开发了解决方案。根据研究计划提出了两个项目。这些项目的显著特点是，它们将实验+建模方法结合起来，以找到实际的CCS解决方案。 项目1：从湿烟气中捕获CO2：大多数关于吸附CO2捕获的报告都考虑了干烟气进料。然而，工业烟道气中的水分饱和（12.5摩尔%），这会对大多数吸附剂的CO2吸附能力产生不利影响。这确实是令人惊讶的是，没有足够的注意力已经支付给理解的影响H2O吸附CO2捕获。项目1将研究高H2O浓度下吸附的基本原理，开发湿烟气CO2捕获工艺并量化所涉及的成本。 项目2：合理的工艺设计和吸附剂选择：吸附工艺有两个重要组成部分：循环和吸附剂。吸附循环是根据过去的经验和有限的模拟+实验设计的。这种方法既不能保证过程得到优化，也不能保证所有可能的配置都得到了探索。在材料方面，新的吸附剂出现了爆炸性增长，例如，金属有机框架（MOFs）。许多性能指标，通常基于平衡信息，已被提出来为特定应用选择正确的吸附剂。由于吸附是一个相当复杂的操作，涉及同时的热/质传递，连同复杂的配置，我们最近已经表明，这些指标不相关的过程性能和使用它们是相当误导。项目2将通过开发基于超结构的优化技术来应对这些挑战，该技术将自动合成复杂的吸附循环;优化其操作条件并为特定分离选择最佳工艺+吸附剂组合。 本文概述的研究计划不仅适用于CO2捕集，还适用于其他重要的气体分离，天然气和页岩气净化，例如，CO2/CH4、CH4/N2分离和烃分离。所有这些分离对阿尔伯塔和加拿大的经济至关重要;每一次分离都代表着数百万美元的生意。 将培养两名博士生和四名本科生。参与该项目的HQP将接受结合实验和数学建模的培训，这是一种相当罕见的组合。他们还将获得一个独特的机会，设计，建造和调试多柱压力/真空变压吸附系统。HQP将在分离工艺的设计和优化，化学工艺设计和强大的沟通技巧方面进行培训;这些属性将使他们能够在选择的职业道路上取得成功。

Carbon capture and storage (CCS) from industrial flue gas is identified by the Canadian government as an important technology to reduce CO2 emissions. For example, a 500 MW coal-based power plant produce ca. 16,000 tonnes of CO2 per day. Capturing CO2 from a dilute flue gas stream (CO2 composition is 12 -15%) and concentrating it to high purities (>90%), using current technologies, e.g., amine-based absorption, is expensive and there is a need to develop alternatives. Adsorption using solid sorbents has been identified as a promising option. The main challenges in adsorptive CO2 capture are: 1. development of novel adsorbents; 2. design and optimization of novel process configurations (cycles) to achieve regulatory targets on purity & recovery > 90%; and 3. experimental demonstration (using wet flue gas) and cost estimation to compare with other technologies. This proposal develops enabling tools for challenge #1 and solutions for #2 & 3. Two projects are proposed under the research program. The distinctive feature of the projects is that they integrate experimental+modelling approaches to find practical CCS solutions. PROJECT 1: CO2 CAPTURE FROM WET FLUE GAS: Most reports on adsorptive CO2 capture have considered a dry flue gas feed. However, industrial flue gas is saturated with moisture (12.5 mol%) which can adversely affect CO2 adsorption capacity of most adsorbents. It is indeed surprising that not enough attention has been paid to the understanding of the effect of H2O on adsorptive CO2 capture. Project 1 will study the fundamentals of adsorption under high H2O concentrations and develop processes for wet flue-gas CO2 capture and quantify the costs involved. PROJECT 2: RATIONAL PROCESS DESIGN & ADSORBENT SELECTION: Adsorption processes have two important constituents: the cycle and the adsorbent. Adsorption cycles are designed based on past experience and limited simulations+experiments. This approach neither guarantees that a process is optimized nor that all possible configurations have been explored. On materials front, there has been an explosive growth of new adsrbents, e.g., metal-organic frameworks (MOFs). Many performance metrics, typically based on equilibrium information, have been proposed to select the right adsorbent for a particular application. Since adsorption is a fairly complex operation involving simultaneous heat/mass transfer, together with intricate configurations, we have recently shown that these metrics do not correlate with process performance and using them is rather misleading. Project 2 will address these challenges through the development of superstructure based optimization techniques which will automatically synthesize complex adsorption cycles; optimize their operating conditions and choose the best process+adsorbent combination for a particular separation. The research program outlined here, will not only be applicable to CO2 capture, but also to other important gas separations, natural and shale gas purification e.g., CO2/CH4, CH4/N2 separations and hydrocarbon separations. All these separations are vital to the economy of Alberta and Canada; each representing a business of the order of millions of dollars. Two PhD and four undergraduate students will be trained. HQP involved in this project will receive training that combines both experimentation and mathematical modelling, a rather rare combination. They will also receive an unique opportunity to design, construct and commission a multi-column pressure/vacuum swing adsorption system. HQP will be trained in design and optimization of separation processes, chemical process design and strong communication skills; attributes that will enable them to be successful in their chosen career paths.