{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,13]],"date-time":"2026-01-13T14:29:59Z","timestamp":1768314599299,"version":"3.49.0"},"reference-count":66,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2023,10,12]],"date-time":"2023-10-12T00:00:00Z","timestamp":1697068800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000038","name":"Natural Sciences and Engineering Research Council (NSERC) of Canada","doi-asserted-by":"publisher","award":["RGPIN\/03882-2020"],"award-info":[{"award-number":["RGPIN\/03882-2020"]}],"id":[{"id":"10.13039\/501100000038","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>A series of petroleum coke (petcoke)-derived solid acid catalysts were prepared via nitric acid treatment with or without ball milling pretreatment. The inherent sulfur in petcoke was converted to sulfonic groups, which were active sites for the esterification of octanoic acid and methanol at 60 \u00b0C, with ester yields of 14\u201343%. More specifically, samples without ball milling treated at 120 \u00b0C for 3 h had a total acidity of 4.67 mmol\/g, which was 1.6 times that of the samples treated at 80 \u00b0C, despite their \u2212SO3H acidities being similar (~0.08 mmol\/g). The samples treated for 24 h had higher \u2212SO3H (0.10 mmol\/g) and total acidity (5.25 mmol\/g) but not increased catalytic activity. Ball milling increased the defects and exposed aromatic hydrogen groups on petcoke, which facilitated further acid oxidation (0.12 mmol \u2212SO3H\/g for both materials and total acidity of 5.18 mmol\/g and 5.01 mmol\/g for BP-N-3\/120 and BP-N-8\/90, respectively) and an increased ester yield. DFT calculations were used to analyze the pathways of sulfonic acid group formation, and the reaction pathway with NO2\u2022 was the most thermodynamically and kinetically favourable. The activities of the prepared catalysts were related to the number of \u2212SO3H acid sites, the total acidity, and the oxygen content, with the latter two factors having a negative impact.<\/jats:p>","DOI":"10.3390\/molecules28207051","type":"journal-article","created":{"date-parts":[[2023,10,12]],"date-time":"2023-10-12T12:46:13Z","timestamp":1697114773000},"page":"7051","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Preparation of Carbon-Based Solid Acid Catalyst from High-Sulfur Petroleum Coke with Nitric Acid and Ball Milling, and a Computational Evaluation of Inherent Sulfur Conversion Pathways"],"prefix":"10.3390","volume":"28","author":[{"given":"Qing","family":"Huang","sequence":"first","affiliation":[{"name":"Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2111-2610","authenticated-orcid":false,"given":"Natalia M.","family":"Cabral","sequence":"additional","affiliation":[{"name":"Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xing","family":"Tong","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada"},{"name":"Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Annelisa S.","family":"Schafranski","sequence":"additional","affiliation":[{"name":"Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3408-9157","authenticated-orcid":false,"given":"Pierre","family":"Kennepohl","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2708-565X","authenticated-orcid":false,"given":"Josephine M.","family":"Hill","sequence":"additional","affiliation":[{"name":"Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1618","DOI":"10.1002\/cjce.22020","article-title":"Characterization, gasification, activation, and potential uses for the millions of tonnes of petroleum coke produced in Canada each year","volume":"92","author":"Hill","year":"2014","journal-title":"Can. 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