Abstract
Ethylene was thermocatalytically transformed into carbon products via a CCVD process. The filamentous carbon obtained was further modified with concentrated sulfuric acid or 4‐benzenediazonium sulfonate (BDS) to produce acid-type catalysts. The as-prepared samples were characterized by SEM and TEM techniques to confirm their morphological features. TG, XRD, elemental, and porosity analyses were also performed to assess the quality of these materials. The fabricated carbons were tested in eco-friendly green synthesis of value-added fuel bio-additives, namely in glycerol esterification. The reaction of glycerol transformation was performed with acetic acid at 80 °C using different glycerol to acetic acid (Gly/AA) molar ratios. The samples functionalized with diazonium salt showed better performance in the above process than those modified with H2SO4, and this was found to be directly related to the degree of surface functionalization with acidic sites. BDS-modified carbon fibers allowed obtaining acceptable results within 6 h when the reaction was performed with a Gly/AA molar ratio of 1:6, however, the dominant products in this case were mono- and diacetins. Extended reaction time altered the distribution of products. Finally, the combined selectivity to the targeted acetins (i.e., DA and TA) was about 75.5%. A direct correlation between the content of –SO3H groups of CNFs and the yield of higher acetins was found.
Highlights
Ethylene was thermocatalytically transformed into carbon products via a CCVD process
Abbreviations CCVD Catalytic chemical vapor deposition TA Triacetin DA Diacetin MA Monocetin methyl tert-butyl ether (MTBE) Methyl tert-butyl ether ETBE Ethyl tert-butyl ether DMF Dimethylformamide CNF1 Carbon fibers obtained with unsupported Ni + 25% C2H4/75%H2 CNF2 Carbon fibers obtained with 10%Ni/CaCO3 + 100% C2H4 TEM Transmission electron microscopy SEM Scanning electron microscopy TG Thermogravimetric analysis X-ray diffraction technique (XRD) X-ray diffraction analysis Gly Glycerol acetic acid (AA) Acetic acid benzenediazonium sulfonate (BDS) 4‐Benzenediazonium sulfonate SBET Apparent surface area Sext External surface area Vtot Total pore volume Vmicro Micropore volume
The Carbon nanofibers (CNFs) samples were modified with sulfuric acid or 4‐benzenediazonium sulfonate (BDS) prepared in situ
Summary
Ethylene was thermocatalytically transformed into carbon products via a CCVD process. BDS-modified carbon fibers allowed obtaining acceptable results within 6 h when the reaction was performed with a Gly/AA molar ratio of 1:6, the dominant products in this case were monoand diacetins. Abbreviations CCVD Catalytic chemical vapor deposition TA Triacetin DA Diacetin MA Monocetin MTBE Methyl tert-butyl ether ETBE Ethyl tert-butyl ether DMF Dimethylformamide CNF1 Carbon fibers obtained with unsupported Ni + 25% C2H4/75%H2 CNF2 Carbon fibers obtained with 10%Ni/CaCO3 + 100% C2H4 TEM Transmission electron microscopy SEM Scanning electron microscopy TG Thermogravimetric analysis XRD X-ray diffraction analysis Gly Glycerol AA Acetic acid BDS 4‐Benzenediazonium sulfonate SBET Apparent surface area Sext External surface area Vtot Total pore volume Vmicro Micropore volume. Sample SO42−/CeO2-ZrO2 PT800S Amberlyst 15 Amberlyst 15 Niobic acid K-10 clay 20%SO4/K10 HZSM-5 25%TPA/Nb2O5 N-based Brønstedacidic ionic liquids Purolite CT-275 OMSC 2 M SO42−/γ-Al2O3 TC-L C_glycerol
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