Theoretical Study on the P-C Bond Dissociation Enthalpy in 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide Flame Retardants.

The 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) flame retardants (DOPO-FRs) have attracted more and more attention in the flame-retardant industry due to their high efficiency, environmental protection, and good molecular design. During the flame-retardant process, the breakage of P-C bonds is very important to the flame-retardant effect. Through the comparison of different density functional theories (DFTs) on P-C BDEs, it was found that MN12-L has the highest calculation accuracy, and the root-mean-square error is the smallest with 1.85 kcal/mol. Therefore, MN12-L was selected to investigate P-C BDEs of different DOPO-FRs including thiophen-amine, benzo[d]thiazol-amine, triazol-amine, and aniline DOPO-FRs. By comparing the theoretical calculation of BDE with the experimental parameters of high limiting oxygen index (LOI) and vertical combustion test (UL-94 test), it was found that the P-C BDEs have a certain correlation with the flame-retardant effect. Finally, based on P-C BDEs, substituent effects, and effective flame-retardant fragments, a series of new DOPO-FRs were designed. The results showed that when only one DOPO fragment was contained, the effective fragments of flame retardants were ranked as furan > thiophene > triazole > imidazole. When bis-DOPO fragment was contained, the flame-retardant effect of diamino-triazole fragments was better than that of benzyldimethylamine fragments. In addition, when the substituents on the effective fragment have two EDGs, the flame-retardant effect is superimposed, which makes the flame-retardant performance more excellent.

Surface Modification by Amino Group Inducing for Highly Efficient Catalytic Oxidation of Toluene over a Pd/KIT-6 Catalyst.

Toluene is one of the typical volatile organic compounds in industry, particularly in energy and fuels production processes, which is required to be eliminated effectively to protect the environment. Catalytic oxidation of toluene is widely studied for its high efficiency, and rational design and synthesis of metal catalysts are keys for toluene oxidation. In this study, an efficient catalyst was designed and synthesized by introducing -NH2 groups on the ordered mesoporous silica (KIT-6) surface to anchor and disperse Pd species, leading to Pd nanoparticles being highly dispersed with uniform particle size distribution. Meanwhile, it was found that the introduction of -NH2 made Pd centers present an electron-rich state, and the active Pd centers could activate O2 molecules to generate more reactive oxygen species and promote the conversion of toluene, which was verified by in situ XPS and O2-TPD characterization. Compared with the catalysts prepared by an impregnation method, the catalytic performance of the Pd/NH2-KIT-6 (0.5 wt %) catalyst was significantly improved. A conversion of 90% for toluene (2400 ppm, 24,000 mL·g-1·h-1) was achieved at 171 °C, and the toluene conversion was maintained above 90% for 900 min, displaying the excellent activity and stability of the Pd/NH2-KIT-6 catalyst.

Aqueous Hydrogenation of Levulinic Acid to 1,4-Pentanediol over Mo-Modified Ru/Activated Carbon Catalyst.

A highly efficient and green process was developed for direct conversion of levulinic acid into 1,4-pentanediol over Mo-modified Ru/activated carbon (AC) catalyst in a continuous fixed-bed reactor. The Ru-MoOx /AC catalyst was found to be efficient for the aqueous-phase hydrogenation of levulinic acid to 1,4-pentanediol, whereby a high yield (96.7 mol %) of 1,4-pentanediol was obtained under mild reaction conditions (70 °C, 4 MPa H2 ).

Conversion of Xylose to Furfuryl Alcohol and 2-Methylfuran in a Continuous Fixed-Bed Reactor.

An efficient process was designed for the synthesis of furfuryl alcohol and 2-methylfuran from xylose using a continuous fixed-bed reactor over a catalyst combining Hß zeolite and Cu/ZnO/Al2 O3 in γ-butyrolactone (GBL)/water as solvent. The cooperative effect of Hß zeolite and GBL facilitated the dehydration of xylose and enhanced largely the furfural yield. The production of furfuryl alcohol and 2-methylfuran can be simply tuned by changing the hydrogenation temperature for furfural over the Cu/ZnO/Al2 O3 catalyst. The yield for furfuryl alcohol reached 87.2 % at 150 °C whereas a yield of 86.8 % was achieved for 2-methylfuran at 190 °C.

One-step Conversion of Furfural into 2-Methyltetrahydrofuran under Mild Conditions.

One-step direct conversion of biomass-derived furfural to 2-methyltetrahydrofuran was realized under atmospheric pressure over a dual solid catalyst based on two-stage-packed Cu-Pd in a reactor; this is the first report that one-step conversion of furfural resulted in high yield of 2-methyltetrahydrofuran (97.1 %) under atmospheric pressure. This strategy provided a successive hydrogenation process, which avoids high H2 pressure, uses the reactor efficiently, and eliminates the product-separation step. Therefore, it could enhance the overall efficiency as a result of low cost and high yield.