Xianjie Li,Bingxiao Feng,Hailin Zhang,Yaping Liu,Meng Xiao,Tingting Huang,Quanhong Zhu,Hongbing Song
Furfural, a key biomass-derived compound, can be transformed into high-value chemicals, including methyl furoate, through oxidative esterification. This process finds broad applications across various industries. In the current study, gold nanoparticles were deposited on γ-Al 2 O 3 pretreated with NaOH etching, utilizing the urea deposit-precipitation method followed by reduction in a hydrogen atmosphere. This approach resulted in a highly active Au catalyst, which was thoroughly characterized using multiple analytical techniques. The optimization of NaOH etching enhanced the pore structure and improved the dispersion of the active metal on the support. Notably, the Au/γ-Al 2 O 3 -2 catalyst, prepared with a 2-hour etching duration using 1 M NaOH, exhibited uniformly dispersed gold nanoparticles with an average size of 2.8 nm. The smaller particle size and enhanced dispersion of these Au nanoparticles significantly contributed to the catalyst’s superior catalytic activity and recyclability. Under optimized reaction conditions, the Au/γ-Al 2 O 3 -2 catalyst achieved nearly complete conversion of 1 mmol of furfural to methyl furoate within 4 h, with both conversion and selectivity exceeding 99 %. The study also proposed a mechanism for the oxidative esterification of furfural to methyl furoate catalyzed by Au/γ-Al 2 O 3 -2. Additionally, the catalyst’s effectiveness in the oxidative esterification of various substrates was investigated, demonstrating its robust activity for aromatic aldehydes and alcohols. This broadens the potential applications of the catalyst in the synthesis of diverse valuable esters.
Xiaolong Deng,Shanshan Wang,Yi Liu,Jiafeng Cao,Jinzhao Huang,Xingwei Shi
In this study, a hierarchical interconnected porous metal sulfide heterostructure was synthesized from CoFeAl layered double hydroxides (LDHs) by a two-step hydrothermal process (sulfidation and a NaOH etching process). Among the as-made samples, the CoFeAl-T-NaOH electrode exhibited excellent oxygen and hydrogen evolution reaction catalytic activities with overpotentials of 344 mV and 197 mV at the current density of 100 mA cm−2, respectively. Meanwhile, small Tafel slopes of 57.7 mV dec−1 and 106.5 mV dec−1 for water oxidation and hydrogen evolution were observed for the CoFeAl-T-NaOH, respectively. Serving as both the cathode and anode for overall water splitting, the CoFeAl-T-NaOH electrode reached a current density of 10 mA cm−2 at a cell voltage of 1.65 V with excellent stability. The enhanced electrocatalytic activity could be attributed to: the hierarchical interconnected nanosheet structure facilitating mass transport; the porous structure promoting electrolyte infiltration and reactant transfer; the heterojunction accelerating charge transfer; and the synergistic effect between them. This study offered a new clue for in situ synthesizing porous transition-metal based heterojunction electrocatalysts with a careful tuning of the sequence of sulfuration and alkaline etching to enhance the electrocatalytic performance.
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