Adsorption equilibria of rhodium acetylacetonate with MCM-41, MSU-H, and HMS silica substrates in supercritical carbon dioxide for preparing catalytic mesoporous materials
Adsorption equilibria of rhodium acetylacetonate with MCM-41, MSU-H, and HMS silica substrates in supercritical carbon dioxide for preparing catalytic mesoporous materials
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DOI：
10.1016/j.supflu.2016.05.032
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发表时间：
2017-02-01
影响因子：
3.9
通讯作者：
Inomata, Hiroshi
中科院分区：
文献类型：
--
作者：
Ushiki, Ikuo;Takahashi, Naoto;Inomata, Hiroshi
采用固定床法测量了三种介孔二氧化硅（MCM-41、MSU-H和HMS）在甲醇共溶剂的超临界二氧化碳（scCO（2））中在313-353 K和15.0 MPa下乙酰丙酮铑（III）（Rh（acac）（3））的吸附等温线。测量的吸附平衡因吸附剂基质而异，并且取决于吸附剂的比表面积和孔结构。由于 CO2 密度的强烈影响，Rh(acac)(3) 的吸附量随着温度的升高而增加。根据数据与 Dubinin-Astakhov (DA) 方程的相关性确定的拟合参数表明，前驱体与吸附剂的相互作用、CO2 密度和吸附剂的孔结构是 scCO(2) 中金属前驱体吸附平衡的主导因素。在 scCO(2) 中采用间歇法对二氧化硅载体进行 Rh 的浸渍可以通过 DA 方程进行表征，其中 E-prec 显示出与浸渍的 Rh 粒径的相关性，而 W-0,(prec) 显示出与 Rh 负载量的相关性。 DA 方程可用于表征 scCO(2) 系统中介孔材料的吸附平衡，并可估计将金属浸渍到介孔二氧化硅基材中所需的条件。 (C) 2016 Elsevier B.V. 保留所有权利。
Adsorption isotherms of rhodium(III) acetylacetonate (Rh(acac)(3)) in supercritical carbon dioxide (scCO(2)) with methanol co-solvent for three types of mesoporous silica (MCM-41, MSU-H, and HMS) at 313-353 K and at 15.0 MPa were measured using a fixed bed method. The measured adsorption equilibria varied among the adsorbent substrates and depended on the specific surface area and pore structure of the adsorbents. The amount of adsorbed Rh(acac)(3) increased with increasing temperature owing to strong effects of the CO2 density. Fitting parameters determined from correlation of the data with the Dubinin-Astakhov (DA) equation demonstrated that the interaction of the precursor for the adsorbents, CO2 density and pore structure of adsorbents were dominant factors in the adsorption equilibria of metal precursors in scCO(2). The impregnation of Rh on the silica supports by a batch method in scCO(2) could be characterized by the DA equation for which E-prec showed correlation with impregnated Rh particle size and W-0,(prec) showed correlation with Rh loading amount. The DA equation is useful for characterizing adsorption equilibria in mesoporous materials with scCO(2) systems and allows estimation of conditions required for impregnating metals into mesoporous silica substrates. (C) 2016 Elsevier B.V. All rights reserved.