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

Abstract

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/Ce0.62Zr0.38O2 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.

Effect of Steam Quality on Extra-Heavy Crude Oil Upgrading and Oil Recovery Assisted with PdO and NiO-Functionalized Al2O3 Nanoparticles

“…The reduction of the surface area was due to the blocking pores for the impregnation of the precursor salts onto the surface of the nanoparticle. These results agree with the reported elsewhere for porous systems doped with transition element oxides [18,23,28,40].…”

“…The colorimetry method was employed to obtain the adsorption amount. The protocol is described in detail in several works [22,23,26,40]. The mass balance showed in Equation ( 1) was used to determine the adsorbed amount of n-C 7 asphaltenes.…”

“…Recently, nanomaterials have been proposed to overcome the different challenges regarding thermal enhanced oil recovery (TEOR) of HO and EHO by decomposing heavy oil fractions like asphaltenes and resins. Some nanoparticles of different chemical nature have been employed, including SiO 2 [4,[18][19][20][21], CeO 2 [22][23][24][25][26][27], TiO 2 [28], and Al 2 O 3 [28,29], among others. The materials are characterized as having a high affinity for heavy oil fractions and reducing the asphaltene decomposition temperature near 300 • C. In search of improving their catalytic activity, the benefits of functionalized materials have been reported in the literature, which with low concentrations of transition metal oxides, can reduce the decomposition temperature close to 200 • C. Some of the most used active phases in literature are Ni [18,19,30,31], Pd [18,23,24], Fe [19,26,32], Co [26,33], and Au [34].…”

“…Some nanoparticles of different chemical nature have been employed, including SiO 2 [4,[18][19][20][21], CeO 2 [22][23][24][25][26][27], TiO 2 [28], and Al 2 O 3 [28,29], among others. The materials are characterized as having a high affinity for heavy oil fractions and reducing the asphaltene decomposition temperature near 300 • C. In search of improving their catalytic activity, the benefits of functionalized materials have been reported in the literature, which with low concentrations of transition metal oxides, can reduce the decomposition temperature close to 200 • C. Some of the most used active phases in literature are Ni [18,19,30,31], Pd [18,23,24], Fe [19,26,32], Co [26,33], and Au [34]. Recently, it has been demonstrated that the functionalized nanoparticles improve the conductivity of porous media, and hence, the heat transfer from the steam to the fluids.…”

Catalytic Conversion of n-C7 Asphaltenes and Resins II into Hydrogen Using CeO2-Based Nanocatalysts

“…The equipment was adjusted at an ion trap linear scan rate of 0.03 m/z between 0 and 200 m/z and an electron impact mode of 100 eV to obtain detailed information of the sample’s gasification. The gases were analyzed following the protocols described elsewhere [ 24 , 49 , 54 , 55 ]. The evolved gases during steam catalytic gasification were evaluated at three different temperatures (210 °C, 220 °C, and 230 °C).…”