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Rapid synthesis of ferrierite zeolite through microwave assisted organic template free route
No full textFerrierite (FER) zeolite has been successfully synthesized within 2-3 h through microwave assisted crystallization without using organic structure directing agent. Crystallization temperature and seed content were found to be two of the key factors. XRD patterns and SEM images of the samples taken at different periods of time revealed that seeds were only partially dissolved during the crystallization process and silicate (alumino) species in the gel grew upon the surface of the partially dissolved seed. A core-shell zeolite growth model was proposed. Compared with original seed zeolite, as-synthesized FER zeolite had more regular morphology and larger particle size. The FER crystal size could be controlled in the range of 0.4-3.0 mu m by adjusting the particle size of the seeds. FER obtained through microwave assisted rapid synthesis showed similar catalytic performance in 1-butene skeletal isomerization with the FER obtained through conventional hydrothermal synthesis
High-performance oxygen evolution electrocatalysis by boronized metal sheets with self-functionalized surfaces
No full textThe oxygen evolution reaction (OER) is a key half-reaction involved in many important electrochemical reactions, but this process is quite sluggish and the materials needed usually show unsatisfactory activity, stability or corrosion resistance in the harsh electrocatalysis environment. Here we report an effective boronization strategy for the value-added transformation of inexpensive, commercially available metal sheets (Ni, Co, Fe, NiFe alloys and steel sheets) into highly active and stable, corrosion resistant oxygen evolution electrodes. The boronized metal sheets exhibit OER activities that are an order of magnitude higher than those of the corresponding metal sheets, and show significantly improved catalytic stability and corrosion resistance in the operating environment. The in situ formed, ultrathin (2-5 nm), metaborate-containing oxyhydroxide thin films on metal boride surfaces are identified as a self-functionalized, highly active catalytic phase for the OER. In particular, a boronized NiFe alloy sheet is demonstrated to exhibit intrinsic catalytic activity higher than those of the state-of-the-art materials in 1 M KOH, while retaining such catalytic activity for over 3000 hours. Additionally, the boronized NiFe alloy and steel sheets are also demonstrated to have good catalytic activity as well as excellent catalytic stability and corrosion resistance in 30% KOH solution, a widely-adopted electrolyte in commercial water-alkali electrolyzers
Corrosion inhibition effects of a novel ionic liquid with and without potassium iodide for carbon steel in 0.5 M HCl solution: An experimental study and theoretical calculation
No full textCorrosion inhibition of carbon steel in 0.5 M HCl solution by novel ionic liquid (IL),1.1'-(1,4-phenylenebis(methylene))bis(3-(carboxymethyl)-1H-imidazol-3-ium) chloride with and without KI was systematically investigated by electrochemical tests, surface and solution analysis as well as theoretical calculation. Results showed that IL can suppress anodic and cathodic reaction by adsorption onto the steel surface, which follows the Langmuir adsorption isotherm. The inhibition efficiency increases with increasing IL concentration. Addition of KI to IL increases the maximum inhibition efficiency of 94.8% to 96.2% when using IL:KI = 1:1. Theoretical inhibition efficiency results correlate well with experimental observations. (C) 2018 Elsevier B.V. All rights reserved
Acid-base synergistic catalysis of biochar sulfonic acid bearing polyamide for microwave-assisted hydrolysis of cellulose in water
No full textThe development of a highly efficient heterogeneous catalysis process for the hydrolysis of cellulose to reducing sugars (RSs) and especially 5-hydroxymethylfurfural (HMF) in water is highly anticipated for large-scale use of cellulosic biomass in the future. Herein, a bamboo-derived biochar sulfonic acid bearing polyamide (BCSA-PA) designed by us was found to show much higher catalytic activity, better repeatability and especially HMF yield for microwave-assisted such hydrolysis compared to the PA-free BCSA, achieving 25.60% RSs and 23.10% HMF yields with 4.71 turnover number (TON) under optimal conditions. Also, its TON value (2.58) for the conversion of cellulose into HMF was much higher than those obtained from it-catalyzed transformation of glucose (TON, 1.44) and especially fructose (TON, 0.79). The BCSA-PA showing an excellent catalysis performance in cellulose hydrolysis is likely due to the following two reasons: (1) the BCSA and especially BCSA-PA, as supported by glucose and cellobiose adsorption experiments, have a stronger affinity to -1,4-glycosidic bonds of cellulose than two monosaccharides, thereby leading to the highly-efficient hydrolysis of cellulose on the SO3H groups. (2) The acid-base synergistic catalysis between the SO3H and PA groups of BCSA-PA may be responsible for its higher HMF selectivity and excellent repeatability in water medium. The current work highlights new opportunities for the direct production of 5-HMF from glucose and especially cellulose.
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