Sensitivity of Asphaltene Aggregation toward the Molecular Architecture under Desalting Thermodynamic Conditions

The challenges faced by the oil and shale industries include the comprehension of the physical–chemical behavior of heavy-weight phases. These phases have a high tendency to aggregate, mainly as a result of the presence of asphaltenes, the composition of which has been fairly unclear up to now. The chemical composition of this phase is one of the driving forces behind the physical–chemical behavior in oil, and the structure–property relations of these systems are key in the development of improved refining techniques, including the design of new catalysts. In this paper, the aggregation of asphaltene molecules is studied with regard to molecular architecture and variations in the size of the aromatic core and lateral chain length using classical molecular dynamics simulations. How these characteristics are impacted by the temperature and pressure is also examined. This analysis provides a general overview of the factors that have the strongest impact on the formation and stability of nanoaggregates and clusters of nanoaggregates

Characterization and Comparison of Trace Metal Compositions in Natural Gas, Biogas, and Biomethane

Biogases are a renewable energy source intended to facilitate the energy transition from natural gas in various domains such as heat and electricity production. The composition of biogas and biomethane is well-known in terms of major compounds, which include methane, carbon dioxide, and hydrogen sulfide. However, the trace element composition of these gases is poorly documented. For the first time, trace metal composition of biomethane produced from agricultural waste and biogas generated at a nonhazardous waste landfill and intended to produce electricity by cogeneration is presented in this work and is compared to the trace metal composition of natural gas. A dedicated high-pressure bubbling sampler was used to sample gas at different operating pressures ranging from 1 to 40 bar. Multiple wide-ranging screenings of metals and metalloids were conducted regarding the elements Se, Cd, Ni, Sb, As, Zn, Pb, Sn, Cr, Ba, Al, V, Mo, Cu, and Ag. The metal concentrations in the sampled natural gas and biomethane were found to be at the same order of magnitude and ranged from 10^–1 to 10² ng/N m³, although some differences in the details were observed. Compared with the metals in those two gases, the metals in the biogas were at higher concentrations, ranging from 1 to 10³ ng/N m³