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In this work, a series of (x)Hf-β zeolite catalysts were prepared by a simple wet impregnation method and used as bifunctional catalysts with Lewis and Brønsted acid sites for synthesizing 5-hydroxymethylfurfural (5-HMF) from cellulose in H

Bimetal mixed MOFs of [CoZn][(BDC)(DABCO)0.5] (CZ-BDO), [CoNi][(BDC)(DABCO)0.5] (CN-BDO), and [NiZn][(BDC)(DABCO)0.5] (NZ-BDO) were prepared under solvothermal conditions and further employed as highly active accelerants for converting carbon dioxide into cyclic carbonates. The characteristics of the bimetal compounds were revealed via various techniques, including ICP-OES, XRD, FT-IR, Raman, XPS, SEM, EDS maps, N2 adsorption, TG-DTG, and CO2/NH3-TPD. The catalytic results revealed that CZ-BDO is superior to the other samples for obtaining a satisfactory chloropropene carbonate (CPC) yield. The excellent catalytic activity may be owing to the presence of a solid solution within the Co and Zn bimetal sample, which provides synergistic catalysis in the carbon dioxide cycloaddition. In addition, the synergistic catalysis was further confirmed by the NH3-TPD profiles, whereby the amount of CZ-BDO basic sites was obviously enhanced compared to the other samples. Furthermore, DFT calculations were also performed to reveal the synergistic catalysis between Co and Zn for the coupling reaction. Additionally, when the coupling reaction was carried out at 100 °C for 5 h in the presence of 0.5 wt% epichlorohydrin (ECH) as a catalyst at 3.0 MPa, 99.31% conversion of ECH and 97.05% yield of CPC were obtained over the optimal CZ-BDO sample. Moreover, the bimetal sample can also efficiently convert other epoxides into the corresponding cyclic carbonates.

Furfural is a promising renewable platform molecule derived from hemi-cellulose, which can be further converted to fossil fuel alternatives and valuable chemicals due to its highly functionalized molecular structure. This mini-review summarizes the recent progress in the chemo-catalytic and/or bio-catalytic conversion of furfural into high-value-added chemicals, including furfurylamine, C6 carboxylic acid, i.e., furandicarboxylic acid, furfural alcohol, aromatics, levulinic acid, maleic acid, succinic acid, furoic acid, and cyclopentanone, particularly the advances in the catalytic valorization of furfural into useful chemicals in the last few years. The possible reaction mechanisms for the conversion of furfural into bio-chemicals are summarized and discussed. The future prospective and challenges in the utilization of furfural through chemo- and bio-catalysis are also put forward for the further design and optimization of catalytic processes for the conversion of furfural.

N,N-dimethylformamide (DMF) is a commonly-used solvent in industry and pharmaceutics for extracting acetylene and fabricating polyacrylonitrile fibers. It is also a starting material for a variety of intermediates such as esters, pyrimidines or chlordimeforms. However, after being used, DMF can be form 5–25% spent liquors (mass fraction) that are difficult to recycle with distillation. From the point of view of energy-efficiency and environment-friendliness, an emergent separation technology, pervaporation, is broadly applied in separation of azeotropic mixtures and organic–organic mixtures, dehydration of aqueous–organic mixtures and removal of trace volatile organic compounds from aqueous solutions. Since the advances in membrane technologies to separate N,N-dimethylformamide solutions have been rarely reviewed before, hence this review mainly discusses the research progress about various membranes in separating N,N-dimethylformamide aqueous solutions. The current state of available membranes in industry and academia, and their potential advantages, limitations and applications are also reviewed.

With the aim of achieving a high 5-hydroxymethylfurfural (HMF) yield from glucose with H-ZSM-5 catalyst at low cost, three inexpensive biphasic reaction systems, H2O—tetrahydrofuran (THF), H2O—2-methyltetrahydrofuran (MeTHF) and H2O’2-butanol, were discovered and proved to be particularly effective in promoting the formation of HMF from glucose over H-ZSM-5 zeolite. In order to determine the optimal process conditions, the effects of various experimental variables, such as reaction temperature, reaction time, catalyst dosage, volume of organic solvent, as well as inorganic salt type on glucose conversion to HMF in three systems were investigated in detail. It was found that under optimal reaction conditions, H2O—THF, H2O—2-butanol and H2O—MeTHF allowed the glucose dehydration process to achieve HMF yields of up to 61%, 59%, and 50%, respectively. Moreover, in the three biphasic systems, the H-ZSM-5 catalyst was also demonstrated to maintain excellent stability. Thus, the catalytic approach proposed in this paper can be believed to have potential prospects for industrially efficient and low-cost production of HMF.

Silica-supported hafinum phosphide (HfP/SiO2) was prepared and applied as an effective solid acid catalyst to drive furfural production from xylan. Various characterizations were employed to analyze the intrinsic properties of the HfP/SiO2 catalyst, and the effects of process parameters on its performance were investigated in detail. The results showed that the performance of the HfP/SiO2 catalyst was excellent, which allowed up to 85% of the furfural yield to be achieved at 180 °C for 60 min in the water(NaCl)/THF biphasic system. There was no significant decrease in the performance of the HfP/SiO2 catalyst after seven consecutive cycles. Characterization analysis of the recovered catalyst revealed that its elemental composition and total acidity were maintained, indicating the desired hydrothermal stability of the HfP/SiO2 catalyst. In addition, by-products produced during xylan conversion were identified as humins and soluble molecular fragments or polymers.

The mesoporous SBA-15 has long been used as an adsorbent for the removal of toxic metal ions. Achieving secondary utilize of spent adsorbent is undoubtedly an advisible option for environmental pro...

In the presented work, a series of Cr/β zeolites were prepared and used as bifunctional catalysts with Bronsted and Lewis acidity in the conversion of biomass-derived carbohydrates to 5‑hydroxymethylfurfural (HMF). The physicochemical properties of all catalysts were characterized by ICP-AES, N2 physisorption, solid-state 27Al NMR, XRD, SEM-EDX, UV–Vis, XPS, Raman, NH3-TPD and Py-FTIR techniques. It was found that the catalysts with appropriate total acidity, ratio of Lewis to Bronsted acid sites and acid density appear to be beneficial for HMF formation. Under mild reaction conditions, a superior 72% HMF yield with 83% selectivity was achieved from glucose in the H2O/THF biphasic system by using the 0.4-Cr/β zeolite catalyst. Moreover, the results of the stability evaluation showed that the catalytic activity of the 0.4-Cr/β zeolite was not significantly lost after four consecutive cycles, and the framework remained intact. Therefore, the catalytic approach proposed in this study is believed to provide potential prospects for the production of HMF from biomass material refining in the future.

[(CH3)2NH2][Co3(BTC)(HCOO)4(H2O)]·H2O (Co-BTC) was synthesized under solvothermal conditions, further used as the precursor for the synthesis of 2-methylimidazole modified Co-BTC (2MeIm@Co-BTC-x). The characteristics of 2MeIm@Co-BTC-x were systematically characterized by various technologies including XRD, FESEM, FT-IR, XPS, N2-adsorption, TG-DTG and CO2/NH3-TPD. It was found that except for the crystal faces (0 1 1) and (− 1 0 2) corresponding to ZIF-67 and Co-BTC, a new crystal phase appeared at 12.22o for the modified Co-BTC, which may be attributed to the coordination between 2MeIm and unsaturated Co ions of Co-BTC. Interestingly, a new structure of hexagonal prisms together with hierarchical porous were also formed for the modified Co-BTC. Besides, when this composite was explored as a heterogeneous catalyst for catalytic conversion of carbon dioxide with epichlorohydrin (ECH) as probe, an obvious enhancement in catalytic activity was obtained compared with the fresh Co-BTC, suggesting that 2MeIm ligands within the modified Co-BTC played a great role on the coupling process. Furthermore, 97.21% of ECH conversion and 98.79% of chloropropene carbonate selectivity were gained over 2MeIm@Co-BTC-1.0 under optimal conditions (3.0 MPa, 90 °C, 5 h, 0.75 wt% catalyst of ECH). Additionally, only a slight decrease in catalytic activity was found after the optimal sample was reused three times. Finally, a mechanism for interpreting the coupling process of carbon dioxide cycloaddition with epoxide was proposed. One-pot catalytic conversion of CO2 into cyclic carbonate over 2-methylimidazole modified Co-BTC

The present work is aimed to investigate the catalytic activities of various Mn-based MOFs for carbon dioxide coupling with epoxides. The metal organic frameworks, [(CH3NH3][Mn(COOH)3] (MA-MnF), [(CH3CH2NH3][Mn(COOH)3] (EA-MnF), and [C3H5N2][Mn(COOH)3] (Im-MnF) were studied via several characterizations such as XRD, FT-IR, XPS, N2-adsorption, TG-DSC, CO2-adsorption and NH3-TPD. Interestingly, Im-MnF compound was observed to possess the highest catalytic activity among the studied compounds, which is associated not only with the amounts of basic sites, but also related to the nitrogen-containing species. 97.27% conversion of allyl-glycidyl ether (AGE, TOF: 36.78 h−1) and 97.66% selectivity to allyl-glycidyl carbonate (AGC) were obtained under the explored optimized conditions (100 °C, 15 bar, 6 h, 1.0 wt% of AGE). In addition, only a slight downward in catalytic activity was found when the sample was reused twice. Furthermore, coupling reactions of CO2 with various epoxides were also performed, of which, the yield of the cyclic carbonates followed the order: Epichlorohydrin > Allyl glycidyl ether > Styrene oxide > Cyclohexene oxide > Propylene oxide. Finally, a mechanism was proposed, which is in good agreement with the DFT calculation.

It is highly desirable to develop a heterogeneous catalyst that is both efficient and recyclable for the simultaneous acquisition of 5-hydroxymethylfurfural (HMF) and furfural from lignocellulose feedstock. Herein, a series of (x)SnCl2-PTA/β catalysts (x = 10, 15, 20, and 25 wt %) were prepared and characterized using ICP-AES, XRD, SEM, N2 adsorption–desorption, XPS, NH3-TPD, and Py-FTIR techniques. It was found that (20)SnCl2-PTA/β catalyst having a suitable acid density, acid ratio, and texture structure contributed to the furan compound formation from carbohydrate components of wheat straw. Under optimal conditions, up to 71% of furfural and 30% of HMF were simultaneously obtained from wheat straw in a water/tetrahydrofuran biphasic system, while the byproducts formed were identified as soluble C4–C15 molecules and insoluble humins. More importantly, the (20)SnCl2-PTA/β catalyst was still capable of providing moderate furan compounds yields after four cycles, and its catalytic performance could be part...

Currently, precious metal catalysts or toxic copper-chromium catalysts are widely used in the catalytic hydrogenation of furfural. In this study, the selective hydrogenation of furfural to furfuryl alcohol was performed over alumina-carbon matrix embedded Ni nanoparticles catalyst. The Ni-loaded metal organic framework precursors were synthesized by reverse microemulsion method (water in oil), then the Ni/Al2O3–C catalysts were obtained by pyrolysis under a nitrogen atmosphere. Various characterizations including XRD, XPS, SEM, TEM, TPR, TPD and TG were carried out to reveal the microstructure and chemical composition of the prepared samples. The results showed that the hexagonal platelet structure and the smaller nickel nanoparticle size(~ 8 nm) benefits from the alumina–carbon matrix support, which helped the uniform dispersion and prevented it from accumulation at high temperatures. In addition, the catalyst performance was greatly affected by the calcination conditions and metal loading. At optimized operating conditions, 98.7% conversion of furfural and 92% yield of furfuryl alcohol could be achieved over Ni0.15/Al2O3–C catalyst in the liquid phase hydrogenation reaction with a good reusability.

A highly active and stable Zn@C/HZSM-5 catalyst with active Zn species and intra-crystalline mesopores for glycerol to aromatics (GTA) was prepared by addition of a Zn@C porous carbon template derived from ZIF-8 into the zeolite synthesis process. XRD, UV-vis DRS, ICP-OES, XPS, TEM, BET, TPD, Py-IR, TGA, and TPO were used to elucidate the correlation between the physicochemical properties and the catalytic performances of the resultant catalysts. The introduced Zn species significantly improved the catalytic activity of Zn@C/HZSM-5 due to the formed Zn-Lewis acid (ZnOH+), which could enhance the aldol condensation and dehydrogenation–aromatization steps in the GTA reaction. Furthermore, the catalytic stability of Zn@C/HZSM-5 was also obviously improved for the simultaneous incorporation of intra-crystalline mesopores. Compared with the inherent micropores in bare HZSM-5, the introduced intra-crystalline mesopores in Zn@C/HZSM-5 not only promoted the diffusion of bulky molecules in zeolite channels and further slowed down coke formation, but also provided more mesopore volume to resist coke deposition, which finally slowed down the catalyst deactivation. Moreover, the Zn introduction methods had significant influences on the Zn state, acidic properties and subsequent catalytic performances of the Zn-modified catalysts. In Zn/HZSM-5(IM) prepared by impregnation, majority of Zn species existed as ZnOH+, and this only remarkably enhanced the aldol condensation step (liquid route), which only resulted in an obvious improvement of the C9 aromatic yield. Whereas in Zn/HZSM-5(PM) prepared by physical mixing, a small fraction of Zn species existed as ZnOH+, which only significantly enhanced the oligomerization step (gas route), leading to a large improvement in the BTX yield. In comparison, Zn@C/HZSM-5 possessed the appropriate ZnOH+ species, which could obviously enhance both the aldol condensation step and oligomerization step in GTA, thus resulting in a superior total aromatics yield for the simultaneous improvements of the BTX yield and C9 aromatic yield. Finally, nearly 100% carbon conversion and 54.7% total aromatics yield were obtained over the stable Zn@C/HZSM-5 with an 8.5 h lifetime due to the synergy between the Zn-Lewis acid (ZnOH+), intra-crystalline mesopores and HZSM-5 zeolite.

The pyrolysis of cyanobacteria provides a promising path for the production of nitrogenous compounds. In this work, several catalysts were prepared and applied to the cyanobacteria pyrolysis. The result showed that the synergistic effect between the acidic catalyst and methanol contributes to the formation of bio-oils and nitrogenous compounds. The yield of nitrogenous compounds increased from 46.79% to over 70% with the help of methanol and an acidic catalyst. Pyrolysis over Ni–Al layered double oxide loaded MCM-41 (NiAl-LDO/MCM-41) provided an optimum bio-oil yield of 26.02%, and 25.82% of the nitrogen in the cyanobacteria was transferred into the bio-oil. Nitriles are the main components in nitrogenous compounds and pentadecanenitrile is the major component of nitriles. Although the bio-oil yield upon pyrolysis over Al2O3 loaded MCM-41 (Al2O3/MCM-41) was only 21.18%, the concentration of nitrogenous compounds in the bio-oil was up to 92.59%, and 87.58% of the bio-oil was made of nitriles, whereas pentadecanenitrile accounted for 78.92%. These results gave us a potential way to obtain nitrogenous compounds such as pentadecanenitrile from renewable resources.

A series of reconstructed hydrotalcite supported monometallic Au or Pd and bimetallic Pd-Au nanoparticles with various Pd/Au ratios were synthesized. The physicochemical properties of these catalysts were charaterized by X-ray diffraction (XRD), X-ray photoelectronic spectroscopy (XPS), Transimission electron microscopy, N2 adsorption, etc. The catalysts were used for the aerobic oxidaiton of 5-hydroxymethylfurfural(HMF) into 2,5-furandicarboxylic acid (FDCA) in an alkaline aqueous solution. The monometallic Pd or Au catalyst could not oxidize the intermediate product-5-hydroxymethyl-2-furanic acid (HMFCA), while bimetallic Pd-Au catalysts exhibited good performances for HMFCA oxidation. A high yield of FDCA up to 90% was achieved over the Pd-Au/HT catalyst with the Au/Pd ratio of 4 at 60 °C for 6 h. The enhanced oxidation activity of HMF for the bimetallic catalysts is attributed to the syneretic effect between Au and Pd nanoparticles and the formation of smaller particle size that facilicates the oxidation of HMF to FDCA. The Pd-Au/HT(1 :4) catalyst also exhibited a good stabiblity without significant loss in FDCA yield after five succesive cycles.

In this study, a series of Fe3+ modified Amberlyst-15 resins (Fe/AR) were prepared and used as environmentally friendly bifunctional catalysts for the conversion of glucose to 5-hydroxymethylfurfural (HMF). The physicochemical properties of the Fe/AR catalysts were characterized by XRD, SEM-EDX, XPS, TG-DTA and FTIR spectroscopy techniques. It was found that the 10%-Fe/AR catalyst has the ability to synergistically catalyze the isomerization of glucose and the dehydration of fructose in a “one-pot” reaction, and allows an impressive 68% HMF yield to be achieved in the H2O/THF biphasic system. Moreover, the 10%-Fe/AR catalyst still retained the desired catalytic activity after four consecutive cycles.

Zn2(C9H3O6)(C4H5N2)(C4H6N2)3 (Zn-BTC-2MeIm) was hydrothermally synthesized and employed as a highly efficient catalyst for CO2 coupling with epichlorohydrin (ECH). Various techniques such as XRD, FT-IR, XPS, TG-DTG, NH3/CO2-TPD were employed for characterizing the compound. Interestingly, TG profile illustrated the Zn-BTC-2MeIm was stable above 200 °C. The highest catalytic activity of 98.93% conversion of ECH and 98.32% selectivity to chloropropene carbonate was observed under the optimum conditions (100 °C, 120 mesh, 1000 rpm, 3.0 MPa, 6 h, 0.75 wt.% of ECH). Besides, the recyclability results exhibited Zn-BTC-2MeIm compound could be reused no less than three times with a slight reduction in its catalytic ability. Moreover, coupling results of CO2 with other epoxides showed this compound could efficiently convert various epoxides into cyclic carbonates. Finally, the investigation of the kinetic exhibited the law of CO2 coupling with ECH was coincident with the first order kinetic and the activation energy (Ea) was to be 113.38 kJ/mol.

Achieving high yields of 5-hydroxymethylfurfural (HMF) from carbohydrates remains a challenge today. With the aim of developing an efficient and inexpensive catalyst for the production of HMF, manganese phosphate (MnPO4) was used as the sole catalyst for the catalytic conversion of biomass-derived carbohydrates into HMF in the H2O/tetrahydrofuran (THF) biphasic reaction system. The effects of various factors, including reaction temperature, reaction time, system, and catalyst dosage on the conversion of carbohydrates to HMF were explored. An impressing HMF yield of 59% was achieved with glucose as a feedstock at 160 °C for 90 min. Meanwhile, up to 44% of HMF was also obtained with microcrystalline cellulose as a feedstock at 170 °C for 120 min. In addition, MnPO4 catalyst also displayed outstanding catalytic activities for the conversion of other biomass-derived carbohydrates including monosaccharides and disaccharides. Combined with the dissolution characteristics of the MnPO4, a possible catalytic mechanism for the conversion of carbohydrates into HMF catalyzed by MnPO4 was proposed. The catalytic approach proposed in this paper exhibited a promising potential for HMF production via optimizing the catalytic process.

Cytochrome P450 (CYP) 2D6, as the only active CYP2D subfamily enzyme in humans, involved in metabolizing 25% of clinical drugs, including antidepressants, antiarrhythmic drugs, antipsychotics and analgesics. Herein, two novel enzyme-activatable fluorescent probes (McMe and BnMcMe) were constructed and synthesized to monitor the activity of CytochromeP4502D6 (CYP2D6) in complex biological systems. McMe possessed excellent selectivity and sensitivity in response to CYP2D6 enzyme with 9-fold fluorescence changes and the limit of detection (LOD) = 0.052 nM. The fruitful application of McMe in living cells and tumor-bearing mice implied that it can be used to measure the activity of endogenous CYP2D6. These researches indicated that McMe could be served as an effective molecular tool to specifically bio-image the activity of endogenous CYP2D6 in nude mice, which may provide assistance to investigate the function of CYP2D6 in drug metabolism and pathologic process.

In the present work, two dual-linker metal-organic frameworks (MOFs) were prepared with metal salts, terephthalic acid and 4, 4′-bipyridine as precursors, and subsequently used for preparing cyclic carbonates from carbon dioxide and epoxides. These two MOFs were characterized by a number of techniques. The two MOFs prepared showed superior catalytic performance under solventless and co-catalyst-free conditions. In this sense, Co(tp)(bpy) achieved epichlorohydrin (ECH) conversions as high as 95.75% and chloropropylene carbonate (CPC) yields of 94.18% under optimal reaction conditions. The high activity of Co(tp)(bpy) was attributed to the co-existence of Lewis acidic and basic active sites on the catalyst derived from incompletely coordinated metal cations and uncoordinated pyridine groups, respectively. In addition, Co(tp)(bpy) maintained this high catalytic performance after five consecutive reaction cycles. A possible reaction mechanism was proposed based on the experimental results.

The present work aimed to investigate the law of the conversion of glycerol with diethyl carbonate (DEC) over the highly efficient Ce–NiO catalyst prepared by co-precipitation method. The thermodynamic and kinetics parameters of this reaction for glycerol carbonate synthesis were studied. The reaction equilibrium constants were investigated experimentally in the temperature region of 338–358 K, and the standard molar properties (at 298 K) were obtained (△H0= 115.71 kJ mol−1, △G0= 13.523 kJ mol−1, △S0= 0.343 kJ mol−1). Effects of various experimental conditions including stirring speed, reaction temperature, catalyst amount, reactant mole ratio on the reaction kinetics were also studied. Different order kinetic equations were used to simulate law of the transesterification process. The result shows a three-order equation of glycerol (two orders) and DEC (one order) was more appropriate to interpret the law of glycerol transesterification with diethyl carbonate. The activation energy of this reaction was obtained with 87.90 kJ mol−1. Finally, the microstructure and physicochemical properties of the Ce–NiO samples were studied by XRD, SEM, TEM, and CO2-TPD. One-pot catalytic conversion of glycerol into glycerol carbonate over Ce–NiO catalyst.

We present here a study of the production of furfural from xylose and wheat straw using the chromium phosphate (CrPO4) with Lewis and Bronsted acidity as a highly efficient catalyst in the water/tetrahydrofuran (THF) biphasic system. The effects of various reaction parameters including reaction temperature, reaction time, system, and catalyst dosage were explored to evaluate the product yield. Under CrPO4 catalysis, an excellent furfural yield could reach 88% from the xylose at 160 °C for 60 min. Meanwhile, 67% furfural and 32% 5‑hydroxymethylfurfura (HMF) were simultaneously achieved from wheat straw at 180 °C for 90 min. Mechanistic studies suggested that the perfect catalytic activity of CrPO4 was due to its inherent bifunctional catalysis activity. It was found that the CrPO4 was easily to be recovered and a great catalytic activity was available after four cycles, which not only contributed to a sustainably reduced energy consumption on catalyst recovery, but also reduced the concerns associated with toxic chromium element.

A series of Fe/β zeolite catalysts with various Fe/Al ratios were prepared by liquid ion-exchanged method and were characterized by N2 adsorption, XRD, UV–Vis DRS, EPR, NH3-TPD, and FTIR of pyridine adsorption techniques. The catalysts were used to catalyze the transformation of glucose into 5-hydorxymethyfural (HMF) in a biphasic reaction system under mild reaction conditions. The Fe/β catalysts with Lewis acidic Fe sites is able to effectively improve the HMF yield compared to H-β zeolite under identical reaction conditions, which is ascribed to the enhanced isomerization activity of glucose-to-fructose by Lewis acidic Fe species. Moreover, the Fe/Al ratio had a remarkable impact on the conversion of glucose and the yield of HMF, indicating that the synergetic effect of Lewis and Bronsted acid sites is critical to achieving high HMF yield. Under optimal reaction conditions, Fe/β-0.06 catalyst afforded 61% HMF yield at glucose conversion of 95% after the reaction of 90 min at 120 °C, which is one of the most effective catalysts for the conversion of glucose into HMF in a biphasic medium up to now. Furthermore, extra-framework isolated Fe species bound to the framework Al sites, are most likely the active sites for the isomerization of glucose-to-fructose in the conversion of glucose. The catalysts were very stable and could be reused at least five runs without significant loss in the catalytic activity.

Herein, the environmentally friendly Fe/β zeolite for glucose isomerization to fructose in aqueous media was reported for the first time. The effects of various reaction conditions including reaction temperature, reaction time, catalyst dosage, etc. on the isomerization reaction over Fe/β zeolite were studied in detail. Under the optimized conditions, yield of fructose higher than 20% were obtained. Moreover, the Fe/β zeolite catalysts were stable and remained constant catalytic activity after five consecutive runs. The possible active Fe species for isomerization of glucose in Fe/β zeolite is also discussed.

A series of carbon nanotube (CNT)-supported monometallic Pd and bimetallic Pd–Fe catalysts were synthesized and employed for catalytic hydrogenolysis of cellulose into polyols, including hexitol, ethylene glycol (EG), 1,2-propanediol (1,2-PG), and glycerol (Gly). The physicochemical properties of the catalysts were characterized by nitrogen physical adsorption measurements, X-ray diffraction analysis, transmission electron microscopy, and X-ray photoelectron spectroscopy. The total yield of hexitol, EG, 1,2-PG, and Gly in hydrolytic hydrogenation of cellulose was 37, 55, and 53% for Pd/CNTs, Pd–Fe/CNTs (Pd:Fe = 1:1), and Pd–Fe/CNTs (Pd:Fe = 1:2), respectively. Addition of Fe to Pd significantly modified the physicochemical properties of the nanoparticles and their catalytic performance, especially regarding hexitol selectivity. The promoting effect of Fe, especially for hexitol selectivity, compared with the monometallic catalyst is due to the fact that incorporation of Fe may stabilize Pd0 nanoparticles and lead to downshift of the d-band center of Pd metal nanoparticles by charge transfer from Fe to Pd. Recycling experimental results showed that leaching of Fe resulted in a significant decrease in the hexitol yield obtained using the Pd–Fe/CNTs after the first recycle, further demonstrating that Fe element plays a promoting role for hexitol formation.

The development of sustainable techniques to convert lignocellulosic materials into value-added chemicals remains a significant challenge. Herein, we report a novel technique to directly convert wheat straw to furan compounds, bio-oils, and phosphate fertilizers. Untreated wheat straw was initially converted into 5-hydroxymethylfurfural (HMF) and furfural in a biphasic reaction system using FePO4 and NaH2PO4 as co-catalyst. The remaining FePO4 in the solid residues was used as the catalyst to pyrolyze the solid residues, producing bio-oils and bio-char-based phosphate fertilizers. This combination of FePO4 and NaH2PO4 co-catalyst exhibited higher selectivity towards HMF and furfural production than using only FePO4 as a catalyst in the conversion of wheat straw. The maximum HMF yield, 44%, was obtained when the reaction was carried out at 160 °C for 60 min, while the highest furfural yield, 92%, was achieved when the reaction occurred at 150 °C for 60 min. This reaction system is one of the most effective reaction systems to date for the conversion of wheat straw. Excessive Bronsted or Lewis acid sites (Fe ions) cannot give high yields of HMF and furfural due to the formation of by-products, indicating that a synergistic combination of Bronsted and Lewis acid sites is critical to obtain high yields of furan compounds. Interestingly, FePO4 could effectively catalyze the pyrolysis of unconverted cellulose into new compounds, such as 5-methylfuran and 2,5-methylfuran, which is not observed in non-catalyzed pyrolysis.

Bimetal mixed MOFs of [CoZn][(BDC)(DABCO)0.5] (CZ-BDO), [CoNi][(BDC)(DABCO)0.5] (CN-BDO), and [NiZn][(BDC)(DABCO)0.5] (NZ-BDO) were prepared under solvothermal conditions and further employed as highly active accelerants for converting carbon dioxide into cyclic carbonates. The characteristics of the bimetal compounds were revealed via various techniques, including ICP-OES, XRD, FT-IR, Raman, XPS, SEM, EDS maps, N2 adsorption, TG-DTG, and CO2/NH3-TPD. The catalytic results revealed that CZ-BDO is superior to the other samples for obtaining a satisfactory chloropropene carbonate (CPC) yield. The excellent catalytic activity may be owing to the presence of a solid solution within the Co and Zn bimetal sample, which provides synergistic catalysis in the carbon dioxide cycloaddition. In addition, the synergistic catalysis was further confirmed by the NH3-TPD profiles, whereby the amount of CZ-BDO basic sites was obviously enhanced compared to the other samples. Furthermore, DFT calculations were also performed to reveal the synergistic catalysis between Co and Zn for the coupling reaction. Additionally, when the coupling reaction was carried out at 100 °C for 5 h in the presence of 0.5 wt% epichlorohydrin (ECH) as a catalyst at 3.0 MPa, 99.31% conversion of ECH and 97.05% yield of CPC were obtained over the optimal CZ-BDO sample. Moreover, the bimetal sample can also efficiently convert other epoxides into the corresponding cyclic carbonates.

In this work, a series of Zn-Co@N-doped carbon materials were prepared by pyrolysis of Co/Zn-ZIF precursors under a N2 atmosphere and used for high-efficiency synthesis of ethyl methyl carbonate (EMC) from dimethyl carbonate (DMC) and diethyl carbonate (DEC). The Co to Zn molar ratio and calcination temperature were varied to study the physical and chemical properties of Zn-Co@N-doped carbon materials identified by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), inductively coupled plasma (ICP), thermogravimetric analysis (TG) and temperature programmed desorption (TPD) analysis. It was deduced that the formation of a ZnO crystalline structure and the interaction between zinc and cobalt providing weak basic sites and strong basic sites, respectively, in different samples significantly affected their catalytic performance. The catalyst activated the reaction most effectively when the Co to Zn molar ratio was 1.0 and calcination temperature was 600 &deg, C. With the DMC to DEC molar ratio controlled at 1:1, a superior yield of around 51.50% of product EMC can be gained over catalyst ZnCo/NC-600 at 100 &deg, C with 1 wt% catalyst loading in 7 h.

It is of great significance to explore and develop a cost-effective and environmentally friendly way to covert cellulosic materials into 5-hydroxymethylfurfural (5-HMF). An inexpensive FePO 4 catalyst, which is insoluble at room temperature but can be partially dissolved and behaves as homogeneous catalyst at elevated temperatures, was used to directly convert cellulose into 5-HMF. The effect of various reaction conditions including reaction temperature, reaction time, cellulose concentration and catalyst amount on the conversion of cellulose and 5-HMF yield was investigated. A 5-HMF yield up to 49.5 mol% was achieved at 160 °C for 60 min with the FePO 4 catalyst, which is comparable to the highest yield of 5-HMF obtained in ionic liquid or homogeneous catalysis reaction systems. Moreover, this unique catalyst is readily separated from the aqueous solution via precipitation after cooling to room temperature since it is insoluble at room temperature. The catalyst can be used over five successive cycles although the amorphous FePO 4 underwent the structural transformation from an amorphous phase into a new crystalline form of FePO 4 , evidenced by XRD, IR, and visible Raman spectroscopic results. The soluble iron species, such as Fe 3 + species, act as Lewis acid sites catalyzing isomerization of glucose to fructose followed by the dehydration of fructose into 5-HMF catalyzed by H + ions.

The highly efficient synthesis of 5-hydroxymethylfurfural (HMF) from carbohydrates was achieved using the inexpensive and bi-functional CrPO4 catalyst in a biphasic system. The effect of various reaction conditions, including reaction temperature, time, and solvent, on HMF yields was explored. A HMF yield of up to 83% was obtained using fructose as the reactant at 140 °C for 15 min. A maximum HMF yield of 63% was also achieved from glucose when the reaction was carried out at 140 °C for 30 min. Among the reported catalysts, CrPO4 was shown to be one of the most effective in the conversion of glucose into HMF, which is comparable to an ionic liquid reaction system. Moreover, the CrPO4 catalyst exhibited high activity to convert microcrystalline and lignocellulosic feedstock to HMF without the need for the addition of homogeneous mineral acids. The possible conversion mechanism of carbohydrates into HMF catalyzed by the bi-functional CrPO4 catalyst is discussed.

In this work, a developed adsorption model was brought forward based on the sigmoid model. Under certain conditions, the model is mathematically equivalent to the hyperbolic model, and it has the ability to predict the adsorption equilibrium time and the adsorption mass of the adsorbent per unit mass of adsorbent in equilibrium. The proposed model can be deduced to the empirical model and other forms under certain conditions. The aim of this study is to obtain a mathematically simplified model, provide a probability to predict related parameters and offer mathematical sights into the Langmuir kinetics. The proposed model is verified through experimental study and the results show that it has a prominent agreement with the experimental data. The model can be dedicated to driving the process of dynamic analysis from fitting to prediction.

5-hydroxymethylfurfural (HMF) is a very important versatile platform compound derived from renewable biomass. The functionalized molecule with an aldehyde group, a hydroxyl group and a furan ring provides great potential for the production of a wide variety of valuable chemicals. This review highlights the latest advances in the catalytic conversion of HMF into value-added chemicals by some important reactions including (1) aerobic oxidation of HMF into furan-based aldehydes and acids such as 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 2,5-diformylfuran (DFF), and furandicarboxylic acid (FDCA), (2) reductive amination of HMF to amine, (3) the synthesis of aromatics by Diels–alder reaction followed by a dehydration reaction, (4) catalytic reduction of HMF into 2,5-bis(hydroxymethyl)furan (BHMF), and 2,5-dimethyl furan (DMF), (5) catalytic oxidation of HMF into maleic anhydride, and some other important transformations. The review mainly focuses on the recent progress in bio-catalytic, electrocatalytic, and heterogeneous catalytic transformation of HMF into high value chemicals over the past few years. Moreover, an outlook is provided to highlight opportunities and challenges related to this hot research topic.

A series of Zn/ZSM-5 catalysts with different Zn contents and FePO4were used to pyrolyze cellulose to produce value added chemicals. The nature of these catalysts was characterized by ammonia-temperature programmed desorption (NH3-TPD), IR spectroscopy of pyridine adsorption, and X-ray diffraction (XRD) techniques. Noncatalytic and catalytic pyrolytic behaviors of cellulose were studied by thermogravimetric (TG) technique. The pyrolytic liquid products, that is, the biooils, were analyzed by gas chromatography-mass spectrometry (GC-MS). The major components of the biooils are anhydrosugars such as levoglucosan (LGA), 1,6-anhydro-β-D-glucofuranose (AGF), levoglucosenone (LGO, 1,6-anhydro-3,4-dideoxy-β-D-pyranosen-2-one), and 1,4:3,6-dianhydro-α-D-glucopyranose (DGP), as well as furan derivatives, alcohols, and so forth. Zn/ZSM-5 samples with Brønsted and Lewis acid sites and the FePO4catalyst with Lewis acid sites were found to have a significant effect on the pyrolytic behaviors of cellulose and product distribution. These results show that Brønsted and Lewis acid sites modified remarkably components of the biooil, which could promote the production of furan compounds and LGO. On the basis of the findings, a model was proposed to describe the pyrolysis pathways of cellulose catalyzed by the solid acid catalysts.

Catalytic conversion of carbohydrates to 5-hydroxymethylfurfural (5-HMF) provides a way toward obtaining renewable biomass-based fuels and chemicals. Herein, we use an inexpensive FePO4 catalyst, which is insoluble at low temperature but can be partially dissolved and act as a homogeneous catalyst at high temperature, in a one-vessel biphasic reactor to generate 5-HMF from carbohydrates such as fructose, glucose, sucrose, cellulose, and Camellia oleifera shell (a lignocellulosic feedstock) without the addition of homogeneous acids. The effects of various reaction conditions including reaction temperature, reaction time, feedstock types and the amount of catalyst on fructose conversion and 5-HMF yield were investigated. The highest 5-HMF yield (71.5 mol%) starting from fructose feedstock was achieved using this “one-pot” biphasic water/tetrahydrofuran (THF) reactor system at 140 °C for 15 min. More interestingly, at high temperature, the FePO4 catalyst was also highly active in the conversion of cellulose and Camellia oleifera shell, which are very difficult to convert to 5-HMF without the addition of mineral acids. A high 5-HMF yield of 48 mol% starting from microcrystalline cellulose was also obtained using the biphasic reaction system. Moreover, the FePO4 catalyst could be easily separated and recycled from the aqueous solution via precipitation after cooling to room temperature since it is insoluble at low temperature. Possible dehydration reaction mechanisms of these carbohydrates catalyzed by FePO4 were also proposed.

The present work aimed to investigate the differences of metal species of [(CH3)2NH2][M(COOH)3](DMA-MF, M = Mn, Co, Ni, Zn) compounds being applied as highly efficient catalysts for enhancing the cycloaddition of CO2 with epoxides. The properties of the as-prepared compounds were systematically investigated via characterizations such as XRD, FT-IR, Raman, XPS, CO2-adsorption, TG-DTG, and CO2/NH3-TPD. The DMA-MnF sample was observed with the highest catalytic activity among the studied MOFs, of which metal node (served as Lewis acid sites) and DMA+ groups (functionalized as Lewis basic sites) within the DMA-MF play a synergistically catalytic effect on the coupling process. Furthermore, when the coupling reaction was carried out at 120 °C for 6 h in presence of 2.0 wt.% PO catalyst under 2.0 MPa, 99.68% conversion of PO and 98.01% yield of propylene carbonate (PC) were perfectly obtained over DMA-MnF compound. In addition, the CO2 coupling with 1, 2-epoxybutane, allyl-glycidyl ether, epichlorohydrin, and styrene oxide were also accomplished under the same conditions. Finally, the DFT calculation was utilized to reveal the appropriate reaction path.