Showing papers by "Changhai Liang published in 2021"

Highly Dispersed Rh/NbOx Invoking High Catalytic Performances for the Valorization of Lignin Monophenols and Lignin Oil into Aromatics

Abstract: As fossil fuels are constantly depleted, valorization of lignocellulosic biomass into valuable aromatic compounds is of great significance but exceedingly challenging. In this work, the structure and catalytic performance of various Rh/Nb₂O₅ catalysts were studied in detail via the catalytic hydrodeoxygenation of a representative lignin monophenol compound 2-methoxy-4-propylphenol. The best catalytic performance was obtained over Rh/Nb₂O₅-400 (Nb₂O₅ calcined at 400 °C) with an exceptional 98% yield of propylbenzene under 0.5 MPa H₂, which was mainly due to the cooperation between highly dispersed Rh metals and NbOₓ species, in which Rh was responsible for dissociation of H₂ and NbOₓ for breaking of C–O bonds at the metal–support interface. Besides, the lignin oil obtained in depolymerization of raw pine wood was directly used as the substrate in the catalytic hydrodeoxygenation reaction over the Rh/Nb₂O₅-400 catalyst under 0.5 MPa H₂. Encouragingly, the liquid products were identified and found that lignin oil was completely converted into C₆–C₁₀ hydrocarbons (>99% selectivity) with an 80.1 mol % yield of aromatics. The results achieved in this work highlighted that high-value utilization of lignocellulosic biomass feedstocks to produce aromatic chemicals and liquid fuels could be achieved over Rh/Nb₂O₅ under a low hydrogen pressure.

Co-production of Naphthenic Oil and Phenolic Compounds from Medium- and Low-Temperature Coal Tar

Abstract: The conversion of medium- and low-temperature coal tar into high-performance fuel and value-added chemicals is one of the main approaches to addressing the current global energy challenges. To this aim, an innovative coal tar processing process has been developed, which enables the efficient transformation. This process is suggested to produce phenolic compounds and naphthenic oil. As the hydrogenation of coal tar involves complex chemical structures and reactions, a systematic matrix of model compounds was presented on the basis of qualitative and quantitative analytics to represent the coal tar and hydrogenation products. The kinetics modeling of tar hydrogenation was proposed to optimize the process parameters and predict the characteristics of products. The energy efficiency (81.62%) and the element utilization (carbon (88.21%), hydrogen (87.13%), and oxygen (31.25%)) associated with the whole process are calculated. From the life cycle assessment, the energy use, the CO₂ emission, and the target costing of the proposed coal tar process are calculated as 10.82 MJ/CNY, 2.71 kg CO₂-eq/CNY, and 3141.2 CNY/t-product, respectively.

Construction of Cu-M-Ox (M = Zn or Al) Interface in Cu Catalysts for Hydrogenation Rearrangement of Furfural

Abstract: Rational design of promising Cu catalyst requires better understanding of the Cu–support perimeter for reactions such as hydrogenation rearrangement of furfural─a pivotal and alternative transforma...

Improving the hydrodesulfurization performance of the sulfur-resistant intermetallic Ni2Si based on a MOF-derived route

Abstract: Carbon-supported intermetallic nickel silicide (Ni2Si/C) as a non-sulfide catalyst derived from Ni-MOF-74 presents high activity and sulphur-resistance in the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The Ni2Si/C catalyst possesses a large specific surface area (168 m2 g−1), small crystallite size (12 nm) and high electronic density of the nickel active sites; thus, they demonstrate HDS properties breaking the metal silicide bottleneck derived from the microelectronic industry during catalysis. Due to the strong electron-donating effect between Ni and Si and the modification effect by a porous carbon matrix, the Ni2Si/C catalyst exhibits an outstanding stability during DBT HDS after 120 h of stability testing.

Modulating the Interaction of NiSO4 and Nb2O5 Boosts the Dimerization of Propylene

Abstract: Propylene dimerization is an attractive way to branch out the bulk chemicals to high-value-added fine chemicals. Based on the coordinatively unsaturated surface sites of nickel and solid acid sites for boosting highly selective dimerization of propylene, a series of NiSO₄/Nb₂O₅ catalysts were synthesized by tuning the synergistic effect through adjusting the calcination temperatures. Under the conditions of 70 °C, 2.5 MPa, and LHSV = 3 h–¹ in a fixed-bed reactor, the NiSO₄/Nb₂O₅-400 catalyst exhibits the highest propylene conversion of ca. 89% with 75% selectivity to C6 products (mainly including 4-methyl-2-pentene and 3-hexene). A possible Cossee–Arlman pathway has been proposed for the dimerization of propylene. In the long-term stability testing, an induction period has been observed, which may be attributed to the coordination of propylene molecules to unsaturated Ni²⁺ cations generating some active nickel species. Subsequently, the NiSO₄/Nb₂O₅-400 catalyst presents a stability up to 30 h. The interesting results inspired us to modulate the interaction of metal (salt) and acid sites to strengthen the selective dimerization of low-carbon olefins.

Nano-Sized NiO Immobilized on Au/CNT for Benzyl Alcohol Oxidation: Influences of Hybrid Structure and Interface.

Abstract: Tiny gold nanoparticles were successfully anchored on carbon nanotubes (CNT) with NiO decoration by a two-step synthesis. Characterizations suggested that Ni species in an oxidative state preferred to be highly dispersed on CNT. During the synthesis, in situ reduction by NaBH4 and thermal treatment in oxidation atmosphere were consequently carried out, causing the formation of Au-Ni-Ox interfaces and bimetal hybrid structure depending on the Ni/Au atomic ratios. With an appropriate Ni/Au atomic ratio of 8:1, Ni atoms migrated into the sub-layers of Au particles and induced the lattice contraction of Au particles, whilst a higher Ni/Au atomic ratio led to the accumulation of NiO fractions surrounding Au particles. Both contributed to the well-defined Au-Ni-Ox interface and accelerated reaction rates. Nickel species acted as structure promoters with essential Au-Ni-Ox hybrid structure as well as the active oxygen supplier, accounting for the enhanced activity for benzyl alcohol oxidation. However, the over-layer of unsaturated gold sites easily occured under a high Ni/Au ratio, resulting in a lower reaction rate. With an Au/Ni atomic ratio of 8:1, the specific rate of AuNi8/CNT reached 185 μmol/g/s at only 50 °C in O2 at ordinary pressure.