Application of templating-free chromium therephtalate for the adsorption of nitrogen-containing compounds in oil refinining feedstocks. Kinetics and thermodinamycs

ABSTRACT

A new simple and high scale hydrothermal synthesis of MIL-101Cr without the use of templating agent was carried out, with yields of up to 83% respective to Cr⁺³ with excellent textural properties. Four samples of MOF were prepared at different reaction times, and, after activation, these were studied for their nitrogen-containing compounds (NCCs) adsorption properties over straight run gasoil-light/cyclic oil (SRGO/LCO) feedstocks from oil refinery processes, containing 400 ppm of N. From the adsorption models studied, the Freundlich isotherm model better fitted the NCCs uptake, with R² up to 0.9982 (RMSE = 0.3). According to the adsorption kinetics experiments, a pseudo second-order behavior (R² = 0.99, RMSE = 0.067) was shown by the adsorbents with 10 min activation time. The max. NCCs adsorption capacity obtained was 19.49 mg/g. Furthermore, from the thermodynamic analysis, a ∆G⁰ as low as −24.6 kJ/mol showed that the adsorption process is extremely spontaneous, implicating excellent applicability at real industrial level. Up to 99.85% of non-reacted Cr⁺³ from MOF synthesis was perfectly recovered by precipitation with ammonia solution. Analysis of the mechanical stirring and static hydrothermal synthesis of MIL-101 Cr did not yield significant difference on the adsorption conditions, which represents an excellent energetically economic process.

KEYWORDS:

• Adsorption
• MIL-101 Cr
• nitrogen compounds
• adsorption kinetics
• fuels

Abbreviations

MIL, Material Institute Lavoisier; NCC, nitrogen-containing compound; SCC, sulfur, containing compound; HDS, hydrodesulphurization; BET, Brunauer–Emmett-Teller; XRD, X-ray diffraction; H₂BDC, terephthalic acid; TMAOH, tetramethylammonium hydroxide; CUS, coordinative unsaturated site; ED, ethylene-diamine; LCO, light cyclic oil.

Acknowledgements

The authors are thankful to the Mexican Petroleum Institute research funds for the financial support granted through the project D.61051. Dr. J. Ascención Montoya and J. A. Toledo-Antonio are greatly acknowledged for their technical advice. Special thanks to pilot plant staff for their technical support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01496395.2022.2069041

Additional information

Funding

This work was supported by the Mexican Petroleum Institute research funds, project number Instituto Mexicano del Petróleo D.61051.