Restructuring Surface Lewis Pairs of FAU Zeolite through N Doping for Boosting the Toluene Side-Chain Alkylation Performance.

Toluene side-chain alkylation with methanol for the styrene monomer formation remains a great challenge. An optimal synergy between acidic and basic sites on zeolites is required for an efficient catalysis process. It is important to modulate the surface Lewis acid-base pairs precisely. Herein, we report a strategy to restructure the surface Lewis acid-base pairs in cesium-modified X zeolite (CsX) by N doping. In the process of toluene side-chain alkylation, the CsX-BN-600 catalyst, where N species is doped into the framework of the X zeolite, exhibits 2.7 times the styrene formation rate and a much better selectivity of 85.7% in comparison to the parent CsX of 70.1% selectivity to styrene at the same reaction conditions. The introduction of N species into zeolites acts as a new Lewis base site and optimizes the Lewis sites due to its ability of electron donation. Meanwhile, the frustrated Lewis pair (FLP) between the deprotonated framework nitrogen in X zeolite and positively polarized C species in the side-chain alkylation reaction is created. Furthermore, the N doping contributes to the generation of the active intermediates of HCOO* and H3CO*. These reasons favor the superiority of the catalyst through N doping.

N-Doped Biochar as a New Metal-Free Activator of Peroxymonosulfate for Singlet Oxygen-Dominated Catalytic Degradation of Acid Orange 7.

In this paper, using rice straw as a raw material and urea as a nitrogen precursor, a composite catalyst (a nitrogen-doped rice straw biochar at the pyrolysis temperature of 800 °C, recorded as NRSBC800) was synthesized by one-step pyrolysis. NRSBC800 was then characterized using XPS, BET, TEM and other technologies, and its catalytic performance as an activator for permonosulfate (PMS) to degrade acid orange 7 (AO7) was studied. The results show that the introduction of N-doping significantly improved the catalytic performance of NRSBC800. The NRSBC800/PMS oxidation system could fully degrade AO7 within 30 min, with the reaction rate constant (2.1 × 10 -1 min-1) being 38 times that of RSBC800 (5.5 × 10-3 min-1). Moreover, NRSBC800 not only had better catalytic performance than traditional metal oxides (Co3O4 and Fe3O4) and carbon nanomaterial (CNT) but also received less impact from environmental water factors (such as anions and humic acids) during the catalytic degradation process. In addition, a quenching test and electron paramagnetic resonance (EPR) research both indicated that AO7 degradation relied mainly on non-free radical oxidation (primarily singlet oxygen (1O2)). A recycling experiment further demonstrated NRSBC800's high stability after recycling three times.

Rice husk biochar modified-CuCo2O4 as an efficient peroxymonosulfate activator for non-radical degradation of organic pollutants from aqueous environment.

A series of rice husk biochar (RHBC) modified bimetallic oxides were prepared using a simple pyrolysis method to activate peroxymonosulfate (PMS) for the degradation of acid orange G (OG). The results demonstrated that 50 mg L-1 OG was completely decomposed by 1 mM PMS activated with 100 mg L-1 RHBC-CuCo2O4 within 15 min at initial pH 3.4. The OG degradation rate constant k of RHBC-CuCo2O4/PMS (0.95 × 10-1 min-1) was five times greater than that of CuCo2O4/PMS (0.19 × 10-1 min-1), suggesting that the introduction of RHBC significantly improved the activity of bimetallic oxides. The effects of the initial pH, catalyst dosage, PMS concentration and reaction temperature on OG removal were also studied. The degradation products of OG were analysed using a gas chromatography-mass spectrometer (GC-MS). Electron paramagnetic resonance (EPR) and quenching experiments showed that singlet oxygen (1O2) was the main active species. The RHBC-CuCo2O4/PMS oxidation system is not only unaffected by inorganic anions (Cl-, NO3 -, HCO3 -) and humic acid (HA), but also could remove other typical pollutants of acetaminophen (ACT), sulfathiazole (STZ), rhodamine B (RhB), and bisphenol A (BPA). These findings show that RHBC-CuCo2O4 has great potential for practical applications in the removal of typical organic pollutants.

CoMn2O4 Catalyst Prepared Using the Sol-Gel Method for the Activation of Peroxymonosulfate and Degradation of UV Filter 2-Phenylbenzimidazole-5-sulfonic Acid (PBSA).

In this study, a bimetallic oxide catalyst of cobalt-manganese (CoMn2O4) was synthesized using the sol-gel method, and it was then characterized using a variety of techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption isotherms. The obtained novel catalyst, i.e., CoMn2O4, was then used as an activator of peroxymonosulfate (PMS) for the catalytic degradation of a commonly-used UV filter, 2-phenylbenzimidazole-5-sulfonic acid (PBSA) in water. The effects of various factors (e.g., catalyst dosage, PMS concentration, reaction temperature, and pH) in the process were also evaluated. Chemical scavengers and electron paramagnetic resonance (EPR) tests showed that the •OH and SO4•- were the main reactive oxygen species. Furthermore, this study showed that CoMn2O4 is a promising catalyst for activating PMS to degrade the UV filters.