Hydroxyalkylation of phenol with formaldehyde to bisphenol F over heteropolyacid impregnated on clay was investigated. These catalysts displayed excellent catalytic performance for this reaction, especially that the effects of acid sites on the isomer distribution are obvious. Various solid catalysts were prepared by impregnating heteropolyacid on different kind of clay matrices, and their chemical compositions, textural properties, and acid strength of the heteropolyacid catalysts were characterized by EDX, BET, NH3-TPD, XRD, and FT-IR. Moreover, the effects of acid sites and reaction temperature on the yield and 4,4′-isomer distribution were launched by comparing the data obtained from the two kinds of catalysts. Furthermore, the kinetics of the hydroxyalkylation of phenol to BPF was established.Hydroxyalkylation of phenol to bisphenol F over heteropolyacid catalysts: The effect of catalyst acid strength on isomer distribution and kinetics.

Hydroxyalkylation of phenol to bisphenol F over the intercalation of aluminum hydroxy oligomeric into layered montmorillonite K10 was investigated. A remarkably high product yield (89.2%) and selectivity to bisphenol F (92.7%) has been achieved at a 110 °C reaction temperature and reaction time of 80 min with a Al-MMT(6) catalyst. A series of catalysts were prepared and characterized by FT-IR, XRD, BET, NH3-TPD and Py-IR. Characterization results showed that the catalytic performance of these catalysts depended on weak and moderate acidity and the textural properties (specific surface areas). The effect of the catalyst calcination temperature to this reaction was also studied. Moreover, the influences of various reaction parameters like mole ratio, catalyst concentration, reaction temperature and reaction time on the product yield and selectivity to bisphenol F were investigated. Finally, the reusability of the catalyst was studied and a plausible mechanistic pathway was proposed.

A series of mesoporous, Al-incorporated, silica-pillared clay (Al-SPCs) interlayer materials with different Al content were prepared in the presence of cationic surfactant by a structure-directing method. The catalysts' structure, texture, and acidic properties were determined using XRD, BET, SEM, TEM, FT-IR, NH3-TPD and Py-IR, respectively. Characterization results showed that these materials possess mesoporous structures with large specific surface areas. The incorporated Al leads to the increase and redistribution of Brönsted and Lewis acid sites on SPC (silica-pillared clay). The Al-SPCs were used as catalysts for hydroxyalkylation of phenol to bisphenol F and gave a high product yield (95.4%) and selectivity (98.2%) to bisphenol F. Catalytic performance of the catalysts and characterization results proved that the catalytic activity of these catalysts depend on moderate acidity and the textural properties (specific surface areas), and the synergy of Brönsted and Lewis acids is key for the hydroxyalkylation of phenol to bisphenol F. The reusability of the catalysts was studied, and they can be easily recovered and reused at least six times without significant loss of their catalytic activities. Finally, a plausible mechanistic pathway was proposed.

In this study, acid-activated palygorskite (Pa) with tunable surface acidity was obtained by simple acidic treatment of raw clay. The new catalysts with 5–30 wt% 12-phosphotungstic acid (H3O40PW12·xH2O, PTA) were then readily prepared by the wet impregnation method. Their characteristic features were systematically investigated by various means including energy-dispersive X-ray (EDX), X-ray diffraction (XRD), N2 adsorption/desorption isotherms, Fourier-transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), as well by comparison with Pa, PTA and H-Beta zeolite. The high activities of these catalysts promoted phenol to undergo hydroxyalkylation, resulting in an interesting bisphenol F (BPF) product. Among these solid acid catalysts, 10% PTA/Pa was chosen as the most suitable catalyst giving an 87% yield and 96% selectivity under mild conditions (phenol/formaldehyde mole ratio of 15:1; T = 343 K; catalyst concentration of 0.006 g g−1; 40 min). The surface acid strength and acidic type were characterized by ammonia temperature programmed desorption of NH3 (NH3-TPD), and FT-IR of pyridine adsorption (Py-IR). It was found that the catalytic activity could be further enhanced by impregnating PTA onto Pa due to the enhanced acid strength and the redistribution of Brönsted and Lewis acid sites. Besides, a more appropriate combination of Brönsted and Lewis acid sites was essential to achieve the highest BPF yield. Recycle experiments were conducted and a plausible mechanistic pathway was proposed according to our observations and findings.

•Popcorn balls-like microsphere photocatalyst.•High photocatalytic activity toward 2,4-DNP degradation.•Degradation kinetics, mechanism, active species were analyzed.•Excellent stable recycling performance.In this paper, novel popcorn balls-like ZnFe2O4-ZrO2 composite microspheres were successfully fabricated by a simple hydrothermal method. The morphology, structure and optical property of the microspheres were characterized. The microspheres were used as the photocatalysts to degrade 2,4-dinitrophenol, and exhibited superior photocatalytic performance. Under simulated solar visible light irradiation, the degradation rate of ZnFe2O4-ZrO2 photocatalyst (mass ratio of ZnFe2O4/ZrO2 = 2:1) was almost 7.4 and 2.4 times higher than those of pure ZnFe2O4 and ZrO2. The enhancement could attribute to stronger light absorption, lower carrier recombination and multi-porous structure of the microspheres. Moreover, the popcorn balls-like photocatalysts can be easily separated, because of the magnetism of the samples. After five times runs, the photocatalyst still showed 90% of its photocatalytic degradation efficiency. This work demonstrated a good prospect for removing organic pollutants in water.