Use of a Dispersed Molybdenum Catalyst and Mechanistic Studies for Upgrading Extra-Heavy Crude Oil Using Methane as Source of Hydrogen

Abstract

A dispersed molybdenum catalyst, derived from MoO 2 (acac) 2 (where acac ) acetylacetonate), was used for upgrading extra-heavy crude oil in the presence of methane as source of hydrogen. The experiments were carried out in a batch reactor at a final CH 4 pressure of 11 MPa, 410 °C, for 1 h. An increase of 7°in the API gravity, 16% of reduction in sulfur content, and 55% conversion of the >500 °C fraction with respect to the original crude was found. The catalyst was analyzed by XPS and EDAX from the coke isolated from the upgrading reaction and it was confirmed that molybdenum is present as MoS 2 . By XPS and SIMS, mechanistic studies were carried out using MoS 2 synthesized on a pure molybdenum sheet. A mechanism for addition of the methane to crude oil is proposed which involves activation of CH 4 by the MoS 2 catalyst generating CH x and H 4-x species on the catalyst surface (where x ) 1, 2, or 3). The CH x moiety can be added to the hydrocarbon molecules, forming methylated products. By carbon isotope ratio mass spectrometry analysis, labeled methane ( 13 CH 4 ) was found to incorporate into the crude oil (estimated value 0.01% w/w) giving conclusive evidence on the involvement of CH 4 in the heavy crude oil upgrading processes.

Downhole Upgrading of Orinoco Basin Extra-Heavy Crude Oil Using Hydrogen Donors under Steam Injection Conditions. Effect of the Presence of Iron Nanocatalysts

“…Also, similar results were obtained previously for extra-heavy crude oil upgrading under higher temperature (380-420 °C) thermal [24] and catalytic conditions (Mo-containing catalyst) [22]. The incorporation of methyl groups, coming from methane, into the crude oil molecules was confirmed by isotopic carbon distribution measurements ( 13 C/ 12 C) using 13 CH4 as a source of hydrogen [22]. However, the addition of methane during the upgrading reaction is very small estimated value (0.01% w/w) and alternative explanations can be suggested as well.…”

“…(1) Egiebor and Gray found methyl-and dimethyl-substituted products by GC analysis of the donor solvent (tetralin), which was attributed to direct alkylation by reaction with methane during iron catalyzed coal liquefaction [23]. Also, similar results were obtained previously for extra-heavy crude oil upgrading under higher temperature (380-420 °C) thermal [24] and catalytic conditions (Mo-containing catalyst) [22]. The incorporation of methyl groups, coming from methane, into the crude oil molecules was confirmed by isotopic carbon distribution measurements ( 13 C/ 12 C) using 13 CH4 as a source of hydrogen [22].…”

“…One plausible explanation could be metal catalyzed incorporation of the methyl groups to the crude oil molecules followed by thermal or catalytic aromatization of the naphthenic compounds, as shown in Equation (1) [22]. (1) Egiebor and Gray found methyl-and dimethyl-substituted products by GC analysis of the donor solvent (tetralin), which was attributed to direct alkylation by reaction with methane during iron catalyzed coal liquefaction [23].…”

“…However, the addition of methane during the upgrading reaction is very small estimated value (0.01% w/w) and alternative explanations can be suggested as well. [22].…”

Scavenging H2S(g) from oil phases by means of ultradispersed sorbents

“…Moreover, ultradispersed catalysis was successfully applied for upgrading of extra heavy oil. Ovalles et al [5] reported a 7°increase in the API gravity, 55% conversion of the heavy fraction and a 16% reduction in the sulfur content using ultradispersed molybdenum catalyst. During heavy oil recovery and upgrading, the sulfur content of heavy oil declines as a result of aqua-thermolysis [6] and hydrodesulfurization [5] reactions, which lead to the evolution of hydrogen sulfide, H 2 S (g) , throughout the oil phase.…”