Effect of Multifunctional Nanocatalysts on n-C7 Asphaltene Adsorption and Subsequent Oxidation under High-Pressure Conditions,Energy & Fuels

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Effect of Multifunctional Nanocatalysts on n-C7 Asphaltene Adsorption and Subsequent Oxidation under High-Pressure Conditions
Energy & Fuels ( IF 5.2 ) Pub Date : 2020-03-29 , DOI: 10.1021/acs.energyfuels.0c00653
Oscar E. Medina ₁ , Jaime Gallego ₂ , Carol M. Olmos ₁ , Xiaowei Chen ₃ , Farid B. Cortés ₁ , Camilo A. Franco ₁

Affiliation

This study was carried out to evaluate the effect of high pressure on the oxidation kinetics of n-heptane asphaltenes in the presence and absence of AuPd/Ce_0.62Zr_0.38O₂ catalysts. Bimetallic Au–Pd catalysts with Au/Pd molar ratios from 3.5 to 9.6 were synthesized by deposition–precipitation of Au and followed by incipient wetness impregnation of Pd (3:1AuPd and 10:1AuPd). Adsorption isotherms between hydrocarbons and nanocatalysts were constructed varying the initial asphaltene concentration from 100 to 1500 mg·L^–1. Subsequent oxidation was evaluated using thermogravimetric analysis under an air atmosphere, at different pressures from 0.084 to 6.0 MPa in a wide temperature range between 100 and 800 °C. Kinetic parameters were calculated using a first-order kinetic model, considering the system pressure. Adsorption affinity increases in the order support < 3:1AuPd < 10:1AuPd. The catalytic activity of the nanocatalyst was highly dependent on the employed temperature and pressure. Their presence reduces the n-C₇ asphaltene decomposition temperature from 450 °C to temperatures below 200 °C for all catalysts used at 6.0 MPa. The main decomposition peaks are presented at 150, 170, and 210 °C for 10:1AuPd, 3:1AuPd, and support, at 6.0 MPa, respectively. Besides, the oxygen chemisorption (OC) region is favored as the material has a greater catalytic activity, increasing from 9.0 to 14.0% (on the load asphaltene basis calculation) for the support and 10:1AuPd catalyst. This was corroborated by the activation energy, which is reduced by more than 30% for all pressures evaluated with the best system. Besides, 89.0 and 80.0% of the mass are lost in the decomposition of the chemisorbed oxygen (DCO) thermal event for the 10:1AuPd and 3:1AuPd nanocatalysts, respectively. Finally, first and second combustions were carried out at temperatures below 240 °C at 6.0 MPa for the 10:1AuPd system, which is a very promising result to determine the reaction pathway for the heavy and extraheavy crude oils during EOR application.

中文翻译：

多功能纳米催化剂对高压条件下n -C ₇沥青吸附及后续氧化的影响

进行该研究以评估在有和没有AuPd / Ce _0.62 Zr _0.38 O ₂催化剂的情况下高压对正庚烷沥青烯氧化动力学的影响。通过沉积-沉淀Au，然后初湿浸渍Pd（3：1AuPd和10：1AuPd），合成了Au / Pd摩尔比为3.5至9.6的双金属Au-Pd催化剂。构建了碳氢化合物和纳米催化剂之间的吸附等温线，其初始沥青质浓度从100到1500 mg·L ^–1。在空气气氛中，在100至800°C的宽温度范围内，在0.084至6.0 MPa的不同压力下，使用热重分析法评估随后的氧化。考虑到系统压力，使用一阶动力学模型计算动力学参数。吸附亲和力以支持度<3：1AuPd <10：1AuPd的顺序增加。纳米催化剂的催化活性高度取决于所采用的温度和压力。它们的存在会降低n -C ₇对于在6.0 MPa下使用的所有催化剂，沥青质的分解温度从450°C到低于200°C。对于10：1AuPd，3：1AuPd和载体，在6.0 MPa时，主要分解峰分别出现在150、170和210°C下。此外，氧化学吸附（OC）区域是有利的，因为该材料具有更大的催化活性，对于载体和10：1AuPd催化剂，其从9.0％增加到14.0％（基于负载沥青质计算）。活化能证实了这一点，对于采用最佳系统评估的所有压力，活化能均降低了30％以上。此外，在10：1AuPd和3：1AuPd纳米催化剂的化学吸附氧（DCO）热事件的分解中，分别损失了89.0％和80.0％的质量。最后，第一次燃烧和第二次燃烧是在低于240°C的温度下于6进行的。

更新日期：2020-03-29

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