Phosphotungstic acid

About: Phosphotungstic acid is a research topic. Over the lifetime, 1925 publications have been published within this topic receiving 38059 citations. The topic is also known as: Phosphowolframic acid.

Catalytic Conversion of Biomass for Aromatics Over HZSM-5 Modified by Dawson-Type Phosphotungstic Acid

Abstract: The multi-functional zeolites modified with different phosphotungstic acid (PW) ratios were prepared and characterized. Thermogravimetric tests coupled with kinetics analysis were performed to evaluate catalytic pyrolysis behavior of biomass; The presence of HZSM-5 inhibited the product diffusion, causing a slight delay of pyrolysis; The PW modification made the reaction more complex; reaction order increased from 1.96 to 2.12. The activation energy decreased from 53.32 to 31.15 kJ/mol with the increase of PW. Then, fixed-bed catalytic experiments were further conducted to investigate aromatics production; 10%PW modification gave the appropriate acidic distribution and pore structure, resulting in oxygen being more likely to be removed in the form of COx. Although the organic yield was only 10.73%, HHV reached 38.01 MJ/kg. The organic phase catalyzed by 10%PW/HZSM-5 exhibited higher aromatization degree, and the structures of benzene ring were mainly single-rings. The oxygenates (especially for phenols from 16.88% to undetected) reduced obviously with increasing PW loading, and the 10%PW modification gave the highest content (peak area, %) of desirable mono-aromatic hydrocarbons (52.29%). The GC/MS analysis results were basically consistent with the 1H/13C NMRs. Besides, the 10%PW/HZSM-5 had the highest catalytic stability and the spent catalyst could recover high activity after regeneration. Therefore, catalytic pyrolysis of biomass using Dawson-structured PW-modified HZSM-5 is a promising approach for production of light aromatic hydrocarbons.

Phosphotungstic acid as a novel acidic catalyst for carbohydrate protection and glycosylation

Abstract: This work demonstrates the utilization of phosphotungstic acid (PTA) as a novel acidic catalyst for carbohydrate reactions, such as per-O-acetylation, regioselective O-4,6 benzylidene acetal formation, regioselective O-4 ring-opening, and glycosylation. These reactions are basic and salient during the synthesis of carbohydrate-based bioactive oligomers. Phosphotungstic acid's high acidity and eco-friendly character make it a tempting alternative to corrosive homogeneous acids. The various homogenous acid catalysts were replaced by the phosphotungstic acid solely for different carbohydrate reactions. It can be widely used as a catalyst for organic reactions as it is thermally stable and easy to handle. In our work, the reactions are operated smoothly under ambient conditions; the temperature varies from 0 °C to room temperature. Good to excellent yields were obtained in all four kinds of reactions.

Encapsulating phosphotungstic acid within metal-organic framework for direct synthesis of dimethyl carbonate from CO2 and methanol

Abstract: Direct synthesis of dimethyl carbonate (DMC) from CO 2 and methanol is a sustainable pathway for DMC production and CO 2 utilization simultaneously. Herein, metal-organic framework MOF-808 with phosphotungstic acid (HPW) encapsulated into the micropore (HPW@MOF-808) prepared by a simple one-pot synthesis method was demonstrated to be an active heterogeneous catalyst for the direct synthesis of DMC with 1,1,1-trimethoxymethane as dehydrate agent. While HPW/MOF-808 sample prepared using impregnation method with HPW mainly aggregated on the surface of MOF-808 matrix was less active. The superior activity of HPW@MOF-808 was attributed to the encapsulation of HPW in the micropore of HPW@MOF-808 enabled more HPW interacting with Zr 6 node to generate more additional HPW induced Bronsted acid sites (Zr-OH) and Lewis acid sites (W + ) than HPW/MOF-808, which promoted the formation of methyl cation (rate-determine step in DMC synthesis) and subsequently accelerated the formation of DMC. Additionally, HPW@MOF-808 exhibited better reusability than HPW/MOF-808 since the interaction between the encapsulated HPW and Zr 6 node inhibited the leaching of HPW during reaction. This work provided a promising strategy for the designing of efficient MOF based catalyst for direct synthesis of organic carbonate from CO 2 and alcohol. HPW@MOF-808 was highly active for the direct synthesis of DMC from CO 2 and CH 3 OH, mainly attributed to the acid sites induced by the encapsulated HPW accelerate the rate-determine step of CH 3 OH activated to CH 3 + . • A novel catalyst HPW@MOF-808 was synthesized via a facile one-pot method. • The encapsulated HPW increased the amount of acidic sites in the catalyst. • HPW@MOF-808 was highly active for the direct synthesis of DMC from CO 2 and methanol with TMM as dehydrate agent. • The additional acidic sites induced by HPW accelerated the rate-determining step of the reaction.

Composition for forming resist underlay film

Abstract: PROBLEM TO BE SOLVED: To provide a composition for forming a resist underlay film showing antistatic property.SOLUTION: The composition for forming a resist underlay film comprises: a resin having a crosslinking moiety; a hetero polyacid by 5 mass% or more and 60 mass% or less with respect to the content of the above resin; and an organic solvent. The composition for forming a resist underlay film may contains, if necessary, a crosslinking agent and a compound that promotes a crosslinking reaction. The crosslinking moiety comprises, for example, a hydroxy group, a carboxyl group or an amino group. The resin having the crosslinking moiety is, for example, an acrylic resin, methacrylic resin, aniline derivative compound, thiophene derivative compound, polyester, or novolac resin. The hetero polyacid is, for example, silicotungstic acid, silicomolybdic acid, phosphomolybdic acid or phosphotungstic acid.