Transition metal phosphides: synthesis nanoarchitectonics, catalytic properties, and biomass conversion applications

Developing inexpensive and efficient catalysts for biomass hydrogenation or hydrodeoxygenation (HDO) is essential for efficient energy conversion. Transition metal phosphides (TMPs), with the merits of abundant active sites, unique physicochemical properties, tunable component structures, and excellent catalytic activities, are recognized as promising biomass hydrogenation or HDO catalytic materials. Nevertheless, the biomass hydrogenation or HDO catalytic applications of TMPs are still limited by various complexities and inherent performance bottlenecks, and thus their future development and utilization remain to be systematically sorted out and further explored. This review summarizes the current popular strategies for the preparation of TMPs. Subsequently, based on the structural and electronic properties of TMPs, the catalytic activity origins of TMPs in biomass hydrogenation or HDO is elucidated. Additionally, the application of TMPs in efficient biomass hydrogenation or HDO catalysis, as well as highly targeted multiscale strategies to enhance the catalytic performance of TMPs, are comprehensively described. Finally, large-scale amplification synthesis, rational construction of TMP-based catalysts and in-depth study of the catalytic mechanism are also mentioned as challenges and future directions in this research field. Expectedly, this review can provide professional and targeted guidance for the rational design and practical application of TMPs biomass hydrogenation or HDO catalysts.

Transition Metal Phosphides (TMP) as a Versatile Class of Catalysts for the Hydrodeoxygenation Reaction (HDO) of Oil-Derived Compounds

Hydrodeoxygenation (HDO) reaction is a route with much to offer in the conversion and upgrading of bio-oils into fuels; the latter can potentially replace fossil fuels. The catalyst’s design and the feedstock play a critical role in the process metrics (activity, selectivity). Among the different classes of catalysts for the HDO reaction, the transition metal phosphides (TMP), e.g., binary (Ni2P, CoP, WP, MoP) and ternary Fe-Co-P, Fe-Ru-P, are chosen to be discussed in the present review article due to their chameleon type of structural and electronic features giving them superiority compared to the pure metals, apart from their cost advantage. Their active catalytic sites for the HDO reaction are discussed, while particular aspects of their structural, morphological, electronic, and bonding features are presented along with the corresponding characterization technique/tool. The HDO reaction is critically discussed for representative compounds on the TMP surfaces; model compounds from the lignin-derivatives, cellulose derivatives, and fatty acids, such as phenols and furans, are presented, and their reaction mechanisms are explained in terms of TMPs structure, stoichiometry, and reaction conditions. The deactivation of the TMP’s catalysts under HDO conditions is discussed. Insights of the HDO reaction from computational aspects over the TMPs are also presented. Future challenges and directions are proposed to understand the TMP-probe molecule interaction under HDO process conditions and advance the process to a mature level.

Recent Advances in the Applications of Mesoporous Silica in Heterogenous Catalysis

Mesoporous silica is a class of silica material with a large specific surface area, high specific pore volume and meso-sized pores. These properties make mesoporous silica a good choice of...

Recent advances in biomass-derived platform chemicals to valeric acid synthesis

A perspective overview for levulinic acid and/or γ-valerolactone to valeric acid synthesis via thermocatalytic and electrocatalytic systems has been summarized.

Hydrotreating of Waste Tire Pyrolysis Oil over Highly Dispersed Ni2P Catalyst Supported on SBA-15

A highly dispersed nickel phosphide catalyst supported on SBA-15 was prepared and tested for the hydrotreating of tire pyrolysis oil (TPO). Physicochemical properties of the prepared catalyst were analyzed by CO uptake chemisorption, BET, TEM, and X-ray diffraction (XRD). An advanced technique with gas chromatography equipped with mass spectrometry and atomic emission detector was applied to investigate carbon-, sulfur-, and nitrogen-containing compounds in TPO. Hydrotreating tests were carried out in a fixed-bed continuous flow reactor at 350 °C, 3.0 MPa, and LHSV of 0.5 h−1. The Ni2P/SBA-15 exhibited an HDS conversion of 89.3% and an HDN conversion of 60.7%, which was comparable to the performance of a commercial NiMoS catalyst under the same conditions.

Transformation of Levulinic Acid to Valeric Biofuels: A Review on Heterogeneous Bifunctional Catalytic Systems

Valerate esters (VAEs) commonly derived from levulinic acid (LA), which is deemed as one of the most promising biomass platform molecules, have been hailed as "valeric biofuels" in recent years. The cascade transformation of LA to VAEs consists of a series of acid- and metal-catalyzed processes alternately, in which heterogeneous bifunctional catalysts are required for better catalytic performance. The transformation pathway from LA to VAEs is presented, and bifunctional catalytic systems for the cascade transformation of LA into valeric acid (VA) and its esters, as well as one-pot conversion processes, are reviewed. Additionally, effects of metal and acid sites on the catalytic performance are discussed in detail. Impacts of and improvements to coke deposition, which is determined to be the primary reason for the reduction in catalytic activity, are also analyzed. Finally, feasible suggestions are proposed for enhanced catalytic performance and a reduction in overall costs.

Selective hydrogenation of CO2 over a Ce promoted Cu-based catalyst confined by SBA-15

Highly efficient generation of methanol and CO relying on the synergistic effect of Cu, ZnO, and CeO_x dispersed in SBA-15.

A simple method to freely adjust the crystalline phase and micro-morphology of NixPy compounds

Different crystalline phase of Ni_xP_y compounds with different morphology were successfully fabricated via a hydrothermal method assisted by urea.