Preparation of Reforming Catalysts

Influence of the Synthesis Method on the Catalytic Behavior of Pt and PtSn/Al2O3Reforming Catalyst

“…On the other hand, to estimate the average particle size from the results of CO chemisorption, the particles were assumed as spheres. The average particle size, d, was calculated from the following equation 21 where d is the average particle size (nm), D is the dispersion, M is the Pt atomic weight, F site is the Pt surface site density (12.5 Pt atoms/nm 2 ), F metal is the Pt density (21.45 g/cm 3 ), and N is the Avogadro constant.…”

“…Therefore, the reaction to produce aromatic compounds is bifunctional since it uses both the metal and the acid sites . In the catalytic reforming (CR) processes, platinum is the active component; it is found dispersed on the surface of an aluminum oxide used as support which has its acidity promoted by the addition of chlorine. − In the late 1960s, the monometallic catalysts were replaced by bimetallic Pt−Re/Al 2 O 3 −Cl catalysts, which were especially promising for low-pressure operation, helping to improve the length of the operation cycles due to a higher coking deactivation resistance, a higher selectivity to aromatic compounds, and a decrease of gas formation. In this context, new trimetallic catalysts have recently appeared in the literature, which are even more selective to isomerized compounds and more resistant to coke deactivation than the bimetallic ones. − …”

Condensation-Enhanced Self-Assembly as a Route to High Surface Area α-Aluminas

“…This is the case for steam reforming − and for the upgrading of heavy oil residues. , Introducing a porous α-alumina is therefore very attractive. The formation of α-alumina is generally carried out by thermal treatment of boehmite at temperatures close to 1200 °C; α-alumina is the ultimate crystallographic phase of the thermal pathway boehmite or pseudoboehmite into γ, δ, θ, and finally α; other routes start with gibbsite treated in a vacuum (ρ, η, θ, and α), gibbsite in air (χ, κ, and α), bayerite in a vacuum (ρ, η, θ, and α), or bayerite in air (η, θ, and α). The side effect of these transformations comes from the high temperature needed to crystallize α-alumina (>1100 °C); this inherently involves considerable sintering or coarsening, or both, and consequently, the particle size increases extensively.…”

“…A method claiming the existence of local hot-spots which leads to α-alumina has been reported as well . In general, these methods have rendered notably high surface areas on the order of 5–15 m 2 g –1 , when θ-alumina has been fully converted into α. Hydrothermal synthesis has been proposed as well − that resembles the low-temperature Diaspore route; Suchanek and Garcés reported an efficient method whereby α-alumina with different morphologies and surface areas, both pure and doped, can be prepared by treating boehmite in the presence of α-alumina seeds and morphology modifiers (e.g., SiO 2 and H 3 BO 3 ) and deionized H 2 O (≥50 wt%). By applying pressure (ca.…”

Selective ring opening of methylcyclohexane and decalin over Rh–Pd supported catalysts: Effect of the preparation method

“…In the case of the S40 series, the total acidity of the SI catalysts is almost 40% lower than that obtained on the CI sample, whereas the preparation method displays no influence on the total acidity of the catalysts supported on Al 2 O 3. In order to explain the differences it must be taken into account that alumina and silica can interact with the impregnation solution, notably by partial dissolution [36,37]. As a consequence, during metal impregnation a certain quantity of Al and Si is dissolved and later precipitate during water elimination.…”