Mexican Institute of Petroleum

About: Mexican Institute of Petroleum is a government organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Catalysis & Asphaltene. The organization has 3273 authors who have published 4170 publications receiving 87269 citations.

Morphology of Aggregated Asphaltene Structural Models

Abstract: Aggregated asphaltene structural models have been generated through a molecular simulation geometry optimization process, using periodic boundary conditions. This methodology has been validated by first applying it to a pure aromatic system. Initially, a random distribution of 35 molecules was chosen and a geometry optimization process was performed, allowing the cell dimensions to vary without restrictions. The structure factor (S(k)) of an optimized final cell was obtained and compared with experimental results, and the agreement between theoretical and experimental S(k) profiles was satisfactory. This methodology was next used in the analysis of the morphology of 32 asphaltene model molecules and their aromatic cores; asphaltene model molecules were taken from literature. It is remarkable that face-to-face stacking of asphaltene aggregates was observed, as well as π-offset and T-shaped stacking geometries. Finally, the effect of aliphatic chains on the aggregates was also analyzed.

Electronic Absorption Edge of Crude Oils and Asphaltenes Analyzed by Molecular Orbital Calculations with Optical Spectroscopy

Abstract: Previous molecular orbital calculations have shown that polycyclic aromatic hydrocarbons (PAHs) with 4−10 fused rings account for the center electronic band positions for bulk asphaltenes. Here, this work is extended to cover low-energy electronic transitions of crude oils and asphaltenes. The primary determinants in optical absorption band location are shown to be the size and geometry of PAHs. Large PAHs are shown to exhibit optical properties exhibited by asphaltenes and crude oils. Furthermore, these results are consistent with the observed Urbach spectral profiles. The rapidly declining electronic absorption at wavelengths exceeding 600 nm is shown to be consistent with the presence of a few large ring systems. Measurements of concentration and temperature independence of crude oil and asphaltene optical spectra imply that potential contributions to their coloration from charge-transfer and potential free radicals are not significant. Nevertheless, the very small electronic absorbances for very low e...

Different process schemes for converting light straight run and fluid catalytic cracking naphthas in a FCC unit for maximum propylene production

Abstract: Light straight run (LSR) and fluid catalytic cracking (FCCN) naphthas were cracked in a transported bed reactor (MicroDowner) and in a fixed bed reactor (MAT) over a commercial Y zeolite based catalyst, over a commercial ZSM-5 zeolite based additive, and over a mixture of both at selected conditions. Based on the mechanisms through which naphtha hydrocarbons are converted, we evaluated the best alternatives for processing these streams to produce light olefins and/or to reduce olefins content in commercial gasoline. The experimental set-up allowed us to simulate the cracking behaviour of the different naphtha streams in a fluid catalytic cracking (FCC) unit by different processing schemes. Results indicate that LSR only cracks at high severity, yielding large amounts of dry gas. Despite its high olefins content, FCCN practically does not crack when it is fed together with gas oil feed. When cracking FCCN alone at typical gas oil cracking conditions, olefins are transformed preferentially into naphtha-range isoparaffins and aromatics, and when cracking FCCN at high severity, olefins are transformed preferentially into propylene and butylenes. Finally, cracking naphtha in the stripper produces some propylene and increases the aromatics in the remaining gasoline.