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Abstract The effect of Na 2 CO 3 , Fe and Na 2 CO 3 + Fe during hydrothermal liquefaction (HTL) of wheat stalk with different temperature and reaction time was investigated in this study. The results indicated that Na 2 CO 3 + Fe can promote the cracking of wheat stalk compared with Na 2 CO 3 or Fe. Meanwhile, higher temperature favored the decomposition of wheat stalk and formation of heavy bio-oil. The highest heavy bio-oil yield was 24.25 wt% and the maximum liquefaction conversion rate was 89.45 wt% in system of Na 2 CO 3 + Fe at 270 °C. The analysis results indicated that longer reaction time could promote liquefaction conversion especially for heavy bio-oil with Na 2 CO 3 + Fe during the process of HTL. GC–MS, UPLC-MS and FT-IR analysis indicated that the major organic compounds in heavy bio-oil were aromatic compounds, alcohols, ketones, alkanes, and aldehydes, among of them aromatic compounds were the most prevalent. [ABSTRACT FROM AUTHOR]

Hydrothermal liquefaction (HTL) of macroalgae residue was accomplished with seven kinds of amine catalysts for chemical and bio-oil production. The effect of HTL conditions on product distribution was investigated, and results showed that both temperature and amines concentration have significant effects on conversion of macroalgae residue to liquid products and bio-oil. The effect of different amines on composition of liquid products and bio-oil was also studied. The main ingredient of liquid products were organic acids, and the yield of organic acids declined with the increase of alkyl chain in amines. The yield of bio-oil increased with the addition of alkyl chain for primary amines and tertiary amines, while decreased for secondary amines. Methylamine had the highest yield of liquid products of 79.09 wt%, and the highest bio-oil yield of 24.37 wt% was obtained in the presence of triethylamine. [ABSTRACT FROM AUTHOR]

The conversion of Undaria pinnatifida residue to glycolic acid was carried out using methylamine as catalyst by hydrothermal method at relatively low temperature. GC–MS and HPLC were used to identify the composition of bio-oil and liquid products which provide the knowledge of the chemical reaction pathways of the hydrothermal liquefaction. The main liquid product was organic acid which contained glycolic acid, lactic acid, formic acid and acetic acid. And the major organic acid was glycolic acid with the highest yield of 46.52% or 33.98% of dry biomass. Methylamine promoted the dissolution of cellulose from Undaria pinnatifida residue, and significantly improved the yield of glycolic acid. The mechanism of HTL was investigated and the results show that the carbocation C 3 was attacked by methylamine molecule which led to the high yield of glycolic acid. In addition, the recovery of methylamine was studied and the highest recovery rate reached 99.28%. [ABSTRACT FROM AUTHOR]

This study investigated the effect of trimethylamine (TMA) on the hydrothermal liquefaction (HTL) process and the recycle of TMA. The results suggest that the peeling reaction occurred on the surface and the cleavage of cellulose leading to water-soluble substances and bio-oil. The highest content of organic acids was found in the water-soluble phase. Model compounds, different glucides with TMA were used to investigate the mechanism of the HTL. Results suggest that the OH − appeared to selectively interact with C–O–C bonds, and thus causing the key linkages of cellulose to become much easier to be cleaved under mild conditions. In addition, the conditions for TMA recovery were optimized and the highest TMA recovery rate reached 98.89%. The recovered TMA had the same properties as the original compound, and it was perfectly re-usable in the conversion process of HTL. [ABSTRACT FROM AUTHOR]

Corn straw can be converted into monophenyl compounds by hydrothermal liquefaction (HTL) in Nano ferrite+inorganic base catalyst system, and dual catalytic systems were favorable for some specific monophenyl compounds in this process. [Display omitted] • HTL of corn straw with Nano ferrite + inorganic base catalyst system was reported. • Highest yield of heavy bio-oil was 34.02 wt% at 180 °C with ZnFe 2 O 4. • Dual catalytic systems were helpful to preparation of mono benzene ring compounds. • Dual catalytic systems have obvious synergistic effect. Hydrothermal liquefaction of corn straw with different catalytic systems and temperatures were investigated in this study. Results showed dual catalytic system can effectively promote the degradation of corn straw at low temperature. With increase of temperature, aqueous phase increased and straw residue decreased for all catalytic systems. The heavy bio-oil yield increased with the increasing of temperature for single catalytic system, while the trend was opposite for dual catalytic system. In single catalytic system, ZnFe 2 O 4 was more suitable for preparation of heavy bio-oil, and the maximum yield reached 34.02 wt% at 180 °C. The proportion of monophenyl compounds in heavy bio-oil for dual catalytic system reached the maximum of 84% at 220 °C with ZnFe 2 O 4. At 180 °C, the contents of Benzofuran,2,3-dihydro and 2-Methoxy-4-vinylphenol reached the maximum of 31.42% and 17.64% in CoFe 2 O 4 catalyst system, and the maximum yield of Vanillin was 10.82% with ZnFe 2 O 4. [ABSTRACT FROM AUTHOR]

Corn straw can be converted into aromatic hydrocarbons and organic acids by hydrothermal liquefaction (HTL), and copper oxide can be reduced to copper powder in this process. • HTL of corn straw with CuO + NaOH, NaOH and CuO was reported. • CuO + NaOH has synergistic effect on production of heavy bio-oil. • Highest yield of heavy bio-oil was 38.2 wt.% at 190 °C. • High temperature can increase the proportion of aromatic compounds in heavy bio-oil. • The maximum ratio of aromatic compounds in heavy bio-oil was 89.84% at 230 °C. In this study, hydrothermal liquefaction (HTL) of corn straw at different operation temperatures, reaction time and catalyst dosage were investigated, and the main product was heavy bio-oil. Results showed that CuO + NaOH have a synergistic effect in the HTL of corn straw. The product distribution and composition were also studied during the process, in which aromatic compounds achieved the highest proportion in heavy bio-oil. Moreover, the yield of aromatic compounds in hydrothermal products increased under simultaneous action of homogeneous and heterogeneous catalysts. The maximum ratio of aromatic compounds was 89.84% under condition of temperature 230 °C, reaction time 1 h, CuO content 3 g and NaOH 100 mL (1 mol·L−1). GC–MS analysis indicated that the major organic compounds in heavy bio-oil at temperatures between 210 °C and 270 °C were interestingly similar. SEM, XRD, H 2 -TPR and XPS analysis showed that CuO was completely reduced to copper in the process. [ABSTRACT FROM AUTHOR]