Liyi Dai

High-quality bio-oil from one-pot catalytic hydrocracking of kraft lignin over supported noble metal catalysts in isopropanol system

Catalytic hydrocracking of kraft lignin was carried out in isopropanol system and an orthogonal array design (OAD) was employed to optimize the experimental conditions. GC-MS/FID, elemental analysis, GPC and (1)H-(13)C HSQC NMR were carried out for entire investigation of the liquid products. The results indicated that the hydrocracking process was thermally controlled and catalysts showed significant influences on the product distributions. Comparing with Pd/C, Pt/C and Ru/C, Rh/C inhibited the self-condensation of isopropanol and reduced the formation of oxygenic-chain compounds. The excellent catalytic activity for phenols conversion was obtained over Rh/C. The routes of oxygenic-chain compounds formation and phenol conversion were proposed in detail. The least oxygenic-chain compounds formation, the highest phenols conversion (93.4%), the lowest O/C ratio (0.094) and the highest HHV (37.969MJ/kg) provided the possibility of the high quality bio-oil obtained over Rh/C in isopropanol medium.

Catalytic ethanolysis and gasification of kraft lignin into aromatic alcohols and H2-rich gas over Rh supported on La2O3/CeO2-ZrO2.

Efficient catalytic ethanolysis and gasification of kraft lignin were conducted over a versatile supported catalyst Rh/La2O3/CeO2-ZrO2 to give high-value aromatic alcohols and H2-rich gas. The removal of phenolic hydroxyl group was the most prevalent reaction, and importantly, almost no phenols, undesired char and saturating the aromatic ring were detected. Meanwhile, the feedstock and solvent both played key roles in H2 generation that contributed to the hydrodeoxygenation of liquid components and made the whole catalytic process out of H2 supply. Reusability tests of catalyst indicated that the crystalline phase transition and agglomeration of support, the loss of noble metal Rh and carbon deposition were the possible reasons for its deactivation in supercritical ethanol. Comparing with water, methanol and isopropanol system, ethanol was the only effective solvent for the depolymerization process.

Additive-assisted Rupe rearrangement of 1-ethynylcyclohexan-1-ol in near-critical water

We performed the Rupe rearrangement of 1-ethynylcyclohexan-1-ol in near-critical water to study the reaction under high temperature conditions. The final product thus obtained was primarily 1-cyclohexen-1-ylethanone which was identified by GC-MS. The influences of reaction time, temperature, and initial reactant-to-water ratio on the yield of 1-cyclohexen-1-ylethanone were examined. The yield of 1-cyclohexen-1-ylethanone was 49 % in pure water at 260°C for a reaction time of 60 min. However, when additives such as ZnSO4, FeCl3, and NaHSO4, respectively, were introduced to the water to investigate the effect of salts on the Rupe rearrangement reaction, the yield increased markedly to as much as 88 % in 5 mole % NaHSO4 aqueous solution under the same conditions. The catalytic ability of the additives decreased in order: NaHSO4, FeCl3, ZnSO4. On the basis of these results, a possible reaction mechanism of the Rupe rearrangement of 1-ethynylcyclohexan-1-ol in near-critical water was proposed.

The effect of tunable graphene oxide sheet size on the structures and catalytic properties of three-dimensional reduced graphene oxide sponge

Based on the selective precipitation of graphene oxide sheets (GOSs), large, medium and small GOSs would be narrowed and controlled by adjusting the time and speed of centrifugation. This size selection principle was used to investigate the influence of GOS size on dispersion, structure, and stacking behavior of GOSs. The structures and catalytic properties of three-dimensional reduced graphene oxide (3D rGO) sponge could also be controlled by the tunable GOS size. These differences due to the different GOS size were correlated to multiscale elemental and structural characteristics of GOSs, such as C/O ratio, the content of oxygen-containing groups on the GO edge, and Raman intensity ratio of D to G-bands of GO on the molecular scale. The relationship between GOS size and the structures and catalytic properties of 3D rGO sponge was established.

Bi-SO3H-functionalized room temperature ionic liquids based on bipyridinium: highly efficient and recyclable catalysts for the synthesis of naphthalene-condensed oxazinone derivatives

Several bi-SO3H-functionalized room temperature ionic liquids were synthesized and their catalytic performances for the synthesis of naphthalene-condensed oxazinone derivatives were studied theoretically, as well as experimentally. Compared with traditional single-SO3H-functionalized ionic liquids, less catalyst and higher yields are the key features of this methodology. Hammett function values and the minimum-energy geometries of bi-SO3H-functionalized ionic liquids were calculated and the results revealed that the acidities and catalytic activities of ionic liquids in the synthesis of naphthalene-condensed oxazinone derivatives were influenced by their structures. There are strong hydrogen bond networks in these bi-SO3H-functionalized ionic liquids. The H–O bond of the sulfonic acid groups was lengthened to different levels compared with the one in the isolated cation. The ionic liquid [(PS)2bPy][OTf]2 with the shortest H–O bond distance had the strongest hydrogen bond and hence showed the strongest acidity and the highest catalytic activity.

Organic solvent extraction-assisted catalytic hydrothermal liquefaction of algae to bio-oil

In this paper, we report our investigation into a two-step method of transformation of algae to bio-oil. Elemental analysis, gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy were used to analyze bio-oil. First, organic solvent Soxhlet extraction and reflux extraction were used in the algal extraction step. Ethanol was proven to be the best solvent, and the addition of MgSO4 could transform acids to esters. In MgSO4 extraction oil, the yield of hexadecanoic acid ethyl ester was as high as 48.40%. Then, the residual algae powders through the catalytic hydrothermal liquefaction process were converted to bio-oil. Commercialized noble metal catalysts Pd/C, Pt/C, Ru/C and Rh/C combined with Pd/HZSM-5 were used in the second step. Rh/C performed the best in the catalytic hydrothermal liquefaction process, and the highest bio-oil yield of 50.98% and HHV of 30.67 MJ kg−1 were achieved. The oil yield through two steps was higher than that by a direct decomposition step. Also, the two-step method could achieve a higher energy conversion ratio of 85.61% and total energy of 81.09 kJ.

Conversion of phenylacetonitrile in supercritical alcohols within a system containing small volume of water

The reaction of phenylacetonitrile in supercritical methanol and ethanol in a system containing a small volume of water was studied. The effects of various operating conditions, such as reaction temperature, reaction time, the mole ratio of phenylacetonitrile/water/methanol or ethanol on the product yield were systematically investigated. The optimal yield of methyl phenylacetate for phenylacetonitrile in supercritical methanol in a system containing a small volume of water was 70 % at 583 K and 2.5 h. The optimal yield of ethyl phenylacetate for phenylacetonitrile in supercritical ethanol with a small volume of water was 80 % at 583 K and 1.0 h. At the same time, a feasible mechanism was proposed for phenylacetonitrile in supercritical methanol and ethanol in a system containing a small volume of water.

Dihydrobenzofuran production from catalytic tandem Claisen rearrangement–intramolecular hydroaryloxylation of allyl phenyl ethers in subcritical water

We herein report a mild method for the preparation of dihydrobenzofurans through hydrothermal catalytic tandem Claisen rearrangement–intramolecular hydroaryloxylation of allyl phenyl ethers. This reaction provides a new method for constructing dihydrobenzofurans, a process that is potentially applicable to natural product synthesis. SBA-15, TS-1, HZSM-5 were chosen as catalysts in a hydrothermal reaction medium between 200 and 320 °C. HZSM-5 catalyst showed the highest catalytic activity, and the effects of molar ratio of allyl phenyl ether–water, time, pressure, temperature and catalyst on the Claisen hydroaryloxylation in hydrothermal condition were investigated. The latter two process variables had the greatest influence on the product yields and distribution. A series of allyl phenyl ether derivatives were also treated in hydrothermal condition with HZSM-5 catalyst to offer high yield of corresponding dihydrobenzofurans.

Orthogonal Array Design for Optimization of Additives Assisted Cycol-Dehydration of 1,4-Butanediol to Tetrahydrofuran in Near-Critical Water

Orthogonal array designs (OAD), OA25 (56), were applied for the first time to optimize cyclo-dehydration of 1,4-butanediol (BD) to tetrahydrofuran (THF)- assisted with additives in near-critical water (NCW) in which the interactions between the variables were temporarily neglected. Six parameters at five levels such as reaction time (t, min), reaction temperature (T,°C), reactant/water ratio (R/W, wt./ wt.), additive/reactant ratio (A/R, wt./wt.), sort of additives and reaction pressure (P, MPa) were investigated. The effects of these parameters were studied by using analysis of variance (ANOVA) to determine the relationship between experimental conditions and levels of yield of THF and conversion of BD. The results showed that the additives had the most significant influence on the yield of THF and conversion of BD, and the other five factors had some advantageous effects on the yield of THF and conversion of BD, however, those effects were much smaller than that of the additives. Finally, the optimal experimental conditions were proposed which could provide the highest yield with respect to the considered factors. Base on these results, a possible reaction mechanism was proposed.