Highly Dispersed Pt Catalysts on Hierarchically Mesoporous Organosilica@Silica Nanoparticles with a Core–Shell Structure for Polycyclic Aromatic Hydrogenation

Abstract

Hydrogenation of naphthalene can effectively reduce the content of aromatics in oil and generate high-value products. A series of Pt-based aluminum-modified core–shell-structured hierarchically periodic mesoporous organosilica@mesoporous silica nanoparticles (Pt/Al-x-PMOs@MSNs) were successfully synthesized and tested for the hydrogenation properties, with preferable mass transfer of macromolecular reactants in the pores and increasing the total acidity of the catalysts. Moreover, the physicochemical properties of the core–shell-structured Pt-based catalysts were systematically analyzed using various characterization techniques. At 300 °C, the naphthalene conversion on the Pt/Al-10-PMOs@MSNs catalyst reached up to 100%, the selectivity of trans-decalin reached 83.9%, and the rate constants (k 1, k2) and TOF were 13.2 × 10–6 mol·g–1·s–1, 1.7 × 10–7 mol·g–1·s–1, and 218.8 h–1, respectively. In the presence of sulfur, the naphthalene hydrogenation over the Pt/Al-10-PMOs@MSN catalyst first decreased to around 40% and then recovered to the original level, which originated from the synergistic effect of the texture and chemical properties over the Pt/Al-10-PMOs@MSNs with an excellent performance.

Increasing Ni Dispersion on a Carbon-Supported Catalyst for Hydrogenation Saturation of Naphthalene: Effect of Different Alkanol Solvents

“…A high-temperature reduction peak at about 450 °C is detected, which is attributed to the reduction of NiO species . The Ni/YP80-EG catalyst prepared by adding ethylene glycol reduces the Ni particle size and improves the dispersion of Ni particles, thus improving the interaction between NiO and the YP80 and making it easier to be reduced by H 2 . Therefore, the reduction temperature of the catalysts set to 450 °C in the reduction experiment could effectively reduce NiO to metallic Ni.…”

“…A nearly 100% NL conversion and nearly 100% DL selectivity were reached for the Ni/YP80-EG catalyst under the conditions of 160 °C and 1.0 MPa H 2 . The main products of the hydrogenation reaction are consistent with TL and DL, which undergo partial hydrogenation to produce TL and then are deeply hydrogenated into DL . TL experiences a reverse reaction of dehydrogenation to generate NL, while it can also be further hydrogenated to DL because TL belongs to the category of light hydrides .…”

“…In particular, a maximum Ni metal surface area of 1.2 m 2 /mg cat and a maximum Ni dispersion of 17.7% were obtained in Ni/YP80-EG. After impregnating with ethylene glycol, the aggregation of Ni particles was inhibited and the interaction of the metal–support was improved for the Ni/YP80-EG catalyst . The turnover frequency (TOF) was calculated by moles of reactant converted divided by moles of the active site for hydrogenation of NL.…”

“…4 The Ni/YP80-EG catalyst prepared by adding ethylene glycol reduces the Ni particle size and improves the dispersion of Ni particles, thus improving the interaction between NiO and the YP80 and making it easier to be reduced by H 2 . 34 Therefore, the reduction temperature of the catalysts set to 450 °C in the reduction experiment could effectively reduce NiO to metallic Ni. As mentioned above, the addition of alkanol solvents improves the interaction between Ni and YP80.…”

“…After impregnating with ethylene glycol, the aggregation of Ni particles was inhibited and the interaction of the metal−support was improved for the Ni/YP80-EG catalyst. 34 The turnover frequency (TOF) was calculated by moles of reactant converted divided by moles of the active site for hydrogenation of NL. The order of the TOF values of the samples is as follows: Ni/YP80-BuOH (0.3 min −1 ) < Ni/YP80-PrOH (1.8 min −1 ) < Ni/YP80-EtOH (5.7 min −1 ) < Ni/YP80-EG (16.5 min −1 ).…”