A computational model for the catalytic hydrogel membrane reactor
A computational model for the catalytic hydrogel membrane reactor
复制标题
催化水凝胶膜反应器的计算模型
DOI：
10.1016/j.watres.2020.116199
复制
发表时间：
2020
期刊：
影响因子：
12.8
通讯作者：
Doudrick, Kyle
中科院分区：
文献类型：
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作者：
Zak, Nicholas;Marks, Randal;Perez-Calleja, Patricia;Nerenberg, Robert;Doudrick, Kyle
催化水凝胶膜反应器（CHMR）是一种很有前途的饮用水水污染物加氢处理新技术。与传统的三相反应器相比，它具有许多优点，包括纳米催化剂的固定化，高反应性和对氢气（H2）供应浓度的控制。在这项研究中，使用AQUASIM开发了CHMR的计算模型，并使用钯（Pd）纳米催化剂（~4.6 nm）对亚硝酸盐（NO2−）还原CHMR的32个实验数据集进行了校准。然后，该模型用于确定影响CHMR行为的关键因素，包括水凝胶催化剂密度、H2供应压力、流入物和本体NO2−浓度以及水凝胶厚度。基于模型校准，NO2−稳态吸附Hinshelwood反应方程的反应速率常数k1和k2分别为0.0039 m3 mole-Pd − 1 s − 1和0.027（mole-H2 m3）1/2 mole-Pd − 1 s −1。反应物通量是CHMR的总NO2−去除速率，受每个催化剂位点的NO2−还原速率的影响，而NO2−还原速率又受可用的NO2−和H2浓度的控制，这些浓度由它们的传质行为调节。反应物在CHMR中的传输是逆扩散的。因此，对于厚的水凝胶，NO2-和H2的同时浓度限制在沿着水凝胶的x-y平面的中间区域沿着，这导致低的总体NO2-去除率（即，通量）。较薄的水凝胶在整个水凝胶中提供更高的并发反应物浓度，导致更高的通量。然而，如果水凝胶太薄，则通量会受到可以加载的Pd量的限制，并且未使用的H2会扩散到主体中并促进生物膜生长。在测试条件下，使NO2−通量最大化的水凝胶厚度在30至150 μm之间。计算模型是第一个描述CHMR行为的模型，是CHMR进一步发展的重要工具。它也可以适用于评估其他污染物或催化剂的CHMR行为，或用于其他类型的界面催化膜反应器。
The catalytic hydrogel membrane reactor (CHMR) is a promising new technology for hydrogenation of aqueous contaminants in drinking water. It offers numerous benefits over conventional three-phase reactors, including immobilization of nano-catalysts, high reactivity, and control over the hydrogen (H2) supply concentration. In this study, a computational model of the CHMR was developed using AQUASIM and calibrated with 32 experimental datasets for a nitrite (NO2−)-reducing CHMR using palladium (Pd) nano-catalysts (~4.6 nm). The model was then used to identify key factors impacting the behavior of the CHMR, including hydrogel catalyst density, H2supply pressure, influent and bulk NO2−concentrations, and hydrogel thickness. Based on the model calibration, the reaction rate constants for the NO2−steady-state adsorption Hinshelwood reaction equation, k1and k2, were 0.0039 m3mole-Pd−1s−1and 0.027 (mole-H2m3)1/2mole-Pd−1s−1, respectively. The reactant flux, which is the overall NO2−removal rate for the CHMR, is affected by the NO2−reduction rate at each catalyst site, which is in turn controlled by the available NO2−and H2concentrations that are regulated by their mass transport behavior. Reactant transport in the CHMR is counter-diffusional. So for thick hydrogels, the concurrent concentrations of NO2−and H2are limiting in the middle region along the x-y plane of the hydrogel, which results in a low overall NO2−removal rate (i.e., flux). Thinner hydrogels provide higher concurrent reactant concentrations throughout the hydrogel, resulting in higher fluxes. However, if the hydrogel is too thin, the flux becomes limited by the amount of Pd that can be loaded, and unused H2can diffuse into the bulk and promote biofilm growth. The hydrogel thickness that maximized the NO2−flux ranged between 30 and 150 μm for the conditions tested. The computational model is the first to describe CHMR behavior, and it is an important tool for the further development of the CHMR. It also can be adapted to assess CHMR behavior for other contaminants or catalysts or used for other types of interfacial catalytic membrane reactors.