Ultradeep Hydrodesulfurization of Feedstock Containing Cracked Gasoil through NiMo/γ-Al₂O₃ Catalyst Pore Size Optimization

Abstract

The importance of ultradeep hydrodesulfurization (HDS) of the cracked and straight run gasoil blend necessitate an extensive study on HDS catalyst optimization. Herein, we report a CO2 assisted neutralization of NaAlO2 aqueous solution conducted in a semibatch membrane dispersion microstructured reactor, as a novel method to synthesize pseudoboehmite powders with different textural properties. A number of γ-Al2O3 catalyst supports as well as NiMo catalysts with the average pore sizes of 6.3 (5.2) to 21.5 (18.6) nm and 5.0 (3.7) to 20.3 (17.2) nm are prepared using the as synthesized pseudoboehmite powders. XRD analysis shows the sizes of all pseudoboehmite and γ-Al2O3 supports crystalline are in the nanoscale range. NH3 TPD results reveal that about half of the total NH3 (1.76 mmol NH3/g) is adsorbed on the surface of γ-Al2O3 support due to presence of strong acidic cites. FTIR spectrometer confirms formation of MoO4 –2 species. The effects of catalyst pore size on HDS performance of the straight run gasoil and its blend with cracked gasoil are also investigated according which, the most sulfur removal from both feedstocks using catalysts with the average pore size of 8.0 (5.9) and 9.1 (7.2) nm, respectively, emphasizing the significant role of the pore size on the catalyst activity and HDS process efficiency. However, effects of textural and physicochemical properties of the catalyst and its support cannot be neglected. The obtained results confirm the proposed synthesis route would be an efficient alternative method to prepare mesoporous γ-Al2O3 supports with precisely controlled average pore size in a wide range of a few up to 20 nm.

Synthesis of NiMo/Al2O3 Nanocatalyst by one pot Co-impregnation Route

“…FTIR spectra of the prepared catalyst are shown in figure (3) Peak in the band (400-1050Cm -1 ) corresponds to MoO3 in (815.12). The absorption bands assigned to the Al-O vibration in (575.46 and 751.21) represent the aluminium ions octahedral and tetrahedral respectively [27,28].These value found in fingerprint region under 1000 cm -1 arising from interatomic vibrations .These results are in agreement with NiMo/Al2O3 the previously reported FTIR spectrum [21,22].When comparing these results with the peaks in figure (4) indicates that results are in agreement with the FTIR of NiMo/γ-Al2O3 previously reported [23]. previously reported [23].…”

Study on Controlled Synthesis of Mesoporous Pseudoboehmite via Carbonation Reaction

“…Pseudoboehmite (PB), as the precursor of mesoporous activated alumina, is widely used as a catalyst or catalyst support and binder in various processes, such as petroleum refining, alcohol dehydration, methanol steam reforming, and Fischer–Tropsch process due to its inexpensiveness, high mechanical strength, and tunable pore size. The methods for preparing pseudoboehmite include neutralization, − alcohol aluminum, − and carbonation reaction methods. − Carbonation reaction of NaAlO 2 solution with CO 2 gas has become one of the most economical techniques for the commercial preparation of PB because the NaAlO 2 solution is an intermediate product of the production process of alumina by bauxite, and the operating cost of flue gas containing carbon dioxide is low. ,− The sodium carbonate wastewater generated by the carbonation reaction can be recycled by smelting bauxite. Thus, research on the preparation of aluminum hydroxide by carbonation reaction has not stopped for nearly 3 decades.…”

Comparison of γ and δ-Al2O3 supported CoMo catalysts in the hydrodesulfurization of straight-run gas oil

“…Alumina is the most common support used for hydrotreating catalyst because of its acceptable mechanical and intrinsic acid-base properties, low-cost prices, and tunable surface physicochemical properties [21][22][23][24][25][26]. The in uence of the nature of the alumina support on the catalyst activity in HDS of straight-run gas oil was scarcely reported.…”