Hollow Carbon Nanospheres Decorated with Abundant Pyridinic N⁺O^– for Efficient Acetylene Hydrochlorination

Considering the disadvantages of metallic catalyst and benchmark commercial activated carbon for acetylene hydrochlorination, such as considerable cost, metal loss, serious carbon deposition, and insufficient active sites, nonmetal hollow carbon nanospherical materials (PACP-T) with hierarchical porous structures were synthesized by the copolymerization of aniline and pyrrole via a self-templating method. Local active sites were constructed by decorating the carbon material with heteroatomic groups. The synthetic process dispersed active sites at the atomic level, which was promoted by local structural forces. Experiments and DFT calculations showed that most active sites were pyridinic N+O–. The superior activity might have been caused by the synergistic adsorption and activation of reactants by highly electronegative heteroatoms and abundant π-containing functional groups (CC, NCN, aromatic ring, and pyridinic N+O–) at active sites on the catalyst. This promoted rapid reactions and impeded carbon deposition, which promoted the continuous exposure of active sites. The significantly improved activity and stability of the optimized PACP-800 catalyst promote its potential industrial applications

Phthalimide Ligand Coordination as a Critical “Key” for Constructing Chlorine–Platinum–Nitrogen Single-Site Catalysts for Effective Acetylene Hydrochlorination

Owing to the low dispersion and deficiency of active species in Pt catalysts, Pt-complexes catalysts (Pt–Lx/SAC–IPA) were synthesized using 2-propanol (IPA) solvent via ligand coordination strategy. The IPA, which exhibits a low boiling point and weak polarity, promotes the dispersion of Pt species. Further, the introduction of phthalimide ligand (L1) modulates the electronic properties of active metals, thereby constructing the single-site-dispersed Cl–Pt–N local structure bearing Pt(II) (presumably the active center of the reaction). Concurrently, the enhanced adsorption and activation performances of the catalyst toward an HCl reactant, as well as its weakened performances toward a C2H2 reactant, improve its anticoking performance and lower the reaction energy barrier. Therefore, the most active Pt–L1/SAC–IPA catalyst achieves an outstanding performance comparable with that of the standard Au/activated carbon (AC)–aqua regia (AR) catalyst, and it is reasonable to conclude that the L1 ligand functioned as a critical “key” in the Pt-based catalytic acetylene hydrochlorination

Computational investigation on adsorption characteristics of aromatic amine for SiHCl₃-BCl₃ system

Recently, after initial rectification, adsorption has become a viable method for further purification of SiHCl3, but much work remains to be done to find a suitable adsorbent. Quantum chemical calculations offers a feasible way to study the mechanism of adsorption, which help develop appropriate adsorbents. Aromatic amines are widely used as adsorbents for BCl3 in SiHCl3, but the adsorption mechanism remains unclear, which impedes the development of efficient adsorbents. In this work, density functional theory is used to investigate the adsorption configuration, adsorption energy and electronic properties of BCl3-SiHCl3 on aromatic amines and the mechanism of interaction between BCl3/SiHCl3 and aromatic amines is analyzed and discussed. The results show that BCl3/SiHCl3 could achieve the separation criteria after two-stage adsorption using aromatic amines (except diphenylamine and triphenylamine) as adsorbent. The adsorption performance decreases as the hydrogen on the nitrogen is gradually replaced by the aromatic ring. When the hydrogen on the benzene ring is substituted with methyl, the adsorption performance of adsorbents changes, which is also position specific. The adsorption energy (-30.63kJ/mol) of p-methylaniline for BCl3 is the highest at 298 K and 1atm. Besides, the desorption behavior of aromatic amines on BCl3 is investigated by increasing the temperature and lowering the pressure by evacuation, and it is found that varying pressure is less energy intensive than increasing the temperature. A combination of adsorption capacity and desorption degree considerations suggest that aromatic amines can be used as adsorbent materials.</p

Construction of Ru–N Single Sites for Effective Acetylene Hydrochlorination: Effect of Polyethyleneimine Modifiers

Several single-site catalysts have been synthesized through the chelation of polyethyleneimine (PEI) with Ru precursors because of the lack of durable active sites in Ru catalysts for acetylene hydrochlorination. Proper thermal activation successfully constructed the local active domains of Ru–N. Ru species were stabilized in their active states by coordinating N in PEI with the central atom Ru in the Ru/activated carbon (AC) catalyst. The metal and highly electronegative heteroatomic sites in the Ru–N domains augmented the activation ability of reactant molecules synergistically. The synthetic strategy developed led to the dispersion of active metal at the level of a single site. Additionally, more Ru–N–C interfaces formed after appropriate pyrolysis of the catalyst (Ru/AC@PEI-T), increasing the contact area to reactants and improving the catalytic efficiency. The modified Ru/AC@PEI catalyst has significantly enhanced catalytic stability over time, allowing for possible industrial applications

Construction of Highly Dispersed Cu–P/Cl Active Sites Using Methyldiphenyloxophosphine for Efficient Acetylene Hydrochlorination

To overcome the disadvantages of Cu-based catalysts, such as the low dispersion of active components and insufficient active species, several 15% Cu-Lx/AC catalysts for acetylene hydrochlorination were synthesized based on strong interactions between a ligand and CuCl2 precursors. The introduction of the methyldiphenyloxophosphine (MDPO) ligand effectively modulated the electronic properties of the metal centers, which contributed to the construction of a highly dispersed Cu–P/Cl local structure with Cu1+/Cu2+ as a plausible active center. The sintering of active components in the catalyst may be one of the main reasons for the decrease in catalytic performance. Meanwhile, the enhanced adsorption and activation of the catalyst for C2H2 and HCl molecules resulted in improved coking resistance. The most active catalyst (15% Cu8MDPO1/AC) could achieve a stable acetylene conversion of 97% at 180 °C, a gas hourly space velocity (GHSV) (C2H2) of 180 h–1, and a feed volume ratio (VHCl/VC2H2) of 1.15, outperforming the benchmark catalyst. The excellent activity and stability in a 300 h laboratory test at a high GHSV and a 3414 h industrial sideline test at an industrial GHSV render the 15% Cu8MDPO1/AC catalyst as a reference for the construction of other catalysts from an environmental, economic, and application prospect perspective