Post Synthesis of Aluminum Modified Mesoporous TUD-1 Materials and Their Application for FCC Diesel Hydrodesulfurization Catalysts

Abstract

Post-synthesis methods are a promising technology and have received much attention. In this paper, a series of post-synthesis aluminum modified TUD-1 (PAT) materials with different Al contents were successfully prepared by using aluminum isopropoxide to be Al sources, then the as-synthesized materials were adopted as support additives mixed with commercial γ-Al 2 O 3 to prepare hydrodesulfurization (HDS) catalysts for FCC diesel. The supports and catalysts were analyzed using N 2 adsorption-desorption, XRD, SEM, Py-IR, ICP, 27 Al MAS NMR, UV-vis, H 2 -TPR and HRTEM techniques. The results of Py-IR and 27 Al MAS NMR indicated that the addition of Al species could bring Lewis (L) and Brönsted (B) sites into Si-TUD-1, and that the material of PAT-3 had the highest total acidity sites and Brönsted acid sites among the series PAT composites. The HRTEM technique showed that, compared to the traditional catalyst NiMo/γ-Al 2 O 3 , the sulfided catalyst NiMo/APAT-3 had a relatively short length (3.2 nm) and suitable stacking number (2.5) of MoS 2 slabs. The HDS efficiencies of all the catalysts were tested in a fixed bed micro-reactor with FCC diesel as feedstock. The catalytic results confirmed that the catalyst NiMo/APAT-3 possessed the highest HDS efficiency (97.0%), due to synergistic effects of advantageous properties such as higher acidity, moderate MSI, and relatively short length of the MoS 2 slabs.

Hydrotreating Performance of FCC Diesel and Dibenzothiophene over NiMo Supported Zirconium Modified Al-TUD-1 Catalysts

“…The presence of Brønsted acidity may be resulted from the electronegativity difference between the Zr and Al atoms. When fabricating Zr atoms into the alumina skeleton, the existence of Zr atoms changes the electronic density around Al, causing the strength weakness of AlO–H bond on the surface of the catalysts, then benefiting to the formation of Brønsted acid sites . Additionally, zirconia species are usually in a coordination number of 7 or 8 but the aluminum ions in alumina material are coordinated in 3, 4 or 5 states, when the octahedral coordinated zirconium atoms are incorporated into the alumina skeleton, the coordination unsaturated positions produce the unoccupied electronic orbits, which result in the formation of Lewis acid sites .…”

Comparative Studies of Carbon Nanomaterial and γ-Alumina as Supports for the Ni–Mo Catalyst in Hydrotreating of Gas Oils

“…However, the downside of using γ-Al 2 O 3 is that extensive research has shown that at the onset of the catalyst preparation stage a strong interaction occurs between the metallic precursor and support that stalls complete sulfidation of the supported metal oxide. , This drawback in complete sulfidation eventually has a negative effect on hydrotreating since a sulfided catalyst in its active form may likely have oxides that might prevent it from working at its fullest potential. Metal–support interaction has a significant impact on HDS efficiency, and moderate metal–support interaction is normally favored …”

“…Metal−support interaction has a significant impact on HDS efficiency, and moderate metal−support interaction is normally favored. 12 Other than the conventional γ-Al 2 O 3 support, the use of alternative supports such as carbon, titania, silica, silica− alumina, and zirconia have gained a lot of research attention not only because they have been proven to yield outstanding hydrotreating performances but also because the use of these alternative supports will circumvent the major challenges encountered with the γ-Al 2 O 3 support. 13−16 The interest in the use of carbon-based support for this study sparked off because carbon is ubiquitous in nature, not prone to nitrogen poisoning and possesses high surface area, controlled pore volume and size.…”

Synthesis of Sulfur-Resistant TiO2-CeO2 Composite and Its Catalytic Performance in the Oxidation of a Soluble Organic Fraction from Diesel Exhaust

“…However, CeO 2 -based catalysts are easily poisoned by SO 2 [21][22][23][24]. And SO 2 is a subsistent in the diesel exhaust, since sulfur is present in almost all commercial diesel fuels [25][26][27], sulfur in fuels would be oxidized to SO 2 and then emitted from diesel engines [28,29]. Furthermore, sulfur poisoning resulting from sulfur species accumulation is more destructive, since even using ultra-low sulfur diesel (ULSD), cumulative exposure of a catalyst over its lifetime in a heavy-duty diesel may amount to kilograms of sulfur [30].…”