Dealuminated Hβ zeolite for selective conversion of fructose to furfural and formic acid

The fructose-to-furfural transformation is facing major challenges in the selectivity and high efficiency. Herein, we have developed a simple and effective approach for the selective conversion of fructose to furfural using Hβ zeolite modified by organic acids for dealuminization to regulate its textural and acidic properties. It was found that citric acid-dealuminized Hβ zeolite possessed high specific surface areas, wide channels and high Brønsted acid amount, which facilitated the selective conversion of fructose to furfural with a maximum yield of 76.2% at433 K for 1 h in the γ-butyrolactone(GBL)-H_(2)O system, as well as the concomitant formation of 83.0% formic acid. The^(13)C-isotope labelling experiments and the mechanism revealed that the selective cleavage of C1–C2 or C5–C6 bond on fructose was firstly occurred to form pentose or C5 intermediate by weak Brønsted acid, which was then dehydrated to furfural by strong Brønsted acid. Also this dealuminized Hβ catalyst showed the great recycling performance and was active for the conversion of glucose and mannose.

Furfural residues derived nitrogen-sulfur co-doped sheet-like carbon: An excellent electrode for dual carbon lithium-ion capacitors

The state-of-the-art lithium-ion capacitors (LICs),consisting of high-capacity battery-type anode and high-rate capacitor-type cathode,can deliver high energy density and large power density when comparing with traditional supercapacitors and lithium-ion batteries,respectively.However,the ion kinetics mismatch between cathode and anode leads to unsatisfied cycling lifetime and anode degradation.Tremendous efforts have been devoted to solving the abovementioned issue.One promising strategy is altering high conductive hard carbon anode with excellent structural stability to match with activated carbon cathode,assembling dual-carbon LIC.In this contribution,one-pot in-situ expansion and heteroatom doping strategy was adopted to prepare sheet-like hard carbon,while activated carbon was obtained involving activation.Ammonium persulfate was used as expanding and doping agent simultaneously.While furfural residues (FR) were served as carbon precursor.The resulting hard carbon (FRNS-HC) and activated carbon (FRNS-AC)show excellent electrochemical performance as negative and positive electrodes in a lithium-ion battery (LIB).To be specific,374.2 m Ah g^(-1)and 123.1 m Ah g^(-1)can be achieved at 0.1 A g^(-1)and 5 A g^(-1)when FRNS-HC was tested as anode.When combined with a highly porous carbon cathode (S_(BET)=2961 m^(2)g^(-1)) synthesized from the same precursor,the LIC showed high specific energy of147.67 Wh kg^(-1)at approximately 199.93 W kg^(-1),and outstanding cycling life with negligible capacitance fading over 1000 cycles.This study could lead the way for the development of heteroatom-doped porous carbon nanomaterials applied to Li-based energy storage applications.

Qualitative analysis of aromatic compounds via 1D TOCSY techniques

The aromatic compounds,including o-xylene,m-xylene,p-xylene,and ethylbenzene,primarily originate from the catalytic reforming of crude oil,and have a wide variety of applications.However,because of similar physical and chemical properties,these compounds are difficult to be identified by gas chromatography(GC)without standard samples.With the development of modern nuclear magnetic resonance(NMR)techniques,NMR has emerged as a powerful and efficient tool for the rapid analysis of complex and crude mixtures without purification.In this study,the parameters of one-dimensional(1D)total correlation spectroscopy(TOCSY)NMR techniques,including 1D selective gradient TOCSY and 1D chemicalshift-selective filtration(CSSF)with TOCSY,were optimized to obtain comprehensive molecular structure information.The results indicate that the overlapped signals in NMR spectra of nonpolar aromatic compounds(including o-xylene,m-xylene,p-xylene and ethylbenzene),polar aromatic compounds(benzyl alcohol,benzaldehyde,benzoic acid),and aromatic compounds with additional conjugated bonds(styrene)can be resolved in 1D TOCSY.More importantly,full molecular structures can be clearly distinguished by setting appropriate mixing time in 1D TOCSY.This approach simplifies the NMR spectra,provides structural information of entire molecules,and can be applied for the analysis of other structural isomers.

含有酰胺基或酯基的可降解阳离子Gemini表面活性剂在水溶液中的 聚集行为

建立高效的可降解表面活性剂是降低表面活性剂对环境污染的重要途径。本工作合成了一系列疏水链或联接基团上含有酰胺基或酯基的可生物降解阳离子Gemini表面活性剂、酰胺基在疏水链的单链表面活性剂以及酰胺基同时在疏水链和联接基团上的Gemini表面活性剂,系统研究了降解基团结构和位置对Gemini表面活性剂聚集行为的影响及Gemini表面活性剂和单体表面活性剂在表面活性和聚集行为方面的差异。结果表明,疏水链带有酰胺键的Gemini表面活性剂C12A-Cn-AC12的临界胶束浓度(cmc)比对应的单链表面活性剂低一个数量级,位于疏水链上的酰胺基可有效促进Gemini表面活性剂C12A-Cn-AC12的氢键形成和自组装。核磁共振氢谱(1H NMR)表明,短联接基团和氢键的共同作用导致C12A-C2-AC12在单体与聚集体间呈现慢交换。对于连接基团含有酰胺键的Gemini表面活性剂(C12-ACnA-C12),酰胺基可明显增加连接基团的有效长度,C12-AC12A-C12在浓度高于cmc时呈现“U”形结构,成为表面活性剂的疏水部分。与只有疏水链或者只有连接基团上含有酰胺键的Gemini表面活性剂相比,连接基团和烷基链上均含有酰胺基的Gemini表面活性剂呈现出更小的cmc和胶束微极性值、更放热的胶束化焓。含酯基的Gemini表面活性剂分子存在醇-酯平衡,且可通过水分子形成的桥连作用形成氢键,比酰胺基间的直接氢键弱,因此,含有酯基的Gemini表面活性剂C12E-C6-EC12和C12-EC6E-C12具有较低的表面活性、较高的胶束离子化度、较大的微极性、聚集过程放热更少。

生物质基酸性低共熔溶剂用于高效溶解木质素及溶解机理

设计能高效溶解木质素的溶剂对木质素的高值化利用具有重要意义。本文中设计了基于氯化胆碱、甜菜碱和左旋肉碱作为氢键受体(HBA)和四种氢键供体(HBD)的生物质衍生的酸性低共熔溶剂(DESs),可以溶解包括碱木质素(AL)、脱碱木质素(DAL)、酶解木质素(EHL)和硫酸盐木质素(KL)在内的不同类型的木质素。在大多数所设计的DESs中,EHL比AL、KL和DAL更容易溶解,而不同木质素中羟基的含量对木质素的溶解有显著影响,但是并非在所有DESs中木质素的溶解情况都符合上述规则。氯化胆碱是构建DESs的首选HBA,具有良好的性能并适应于不同类型木质素的溶解,而合适的酸度使苯甲酸和没食子酸乙酯成为对木质素溶解有利的HBDs。研究表明能有效溶解木质素的DESs应具有强的氢键酸度(α值>0.95)以及与溶解的木质素匹配的合适极性。此外,HBD的pKa值和DESs的酸度也是评价酸性DESs溶解木质素性能的有效指标。通常具有适中pKa值的HBDs能够用于构建具有高效的木质素溶解性能的DESs。DESs的粘度对木质素溶解也有一定影响,较低的粘度有助于木质素溶解。

Improvement of low temperature activity and stability of Ni catalysts with addition of Pt for hydrogen production via steam reforming of ethylene glycol

Hydrogen production by steam reforming of ethylene glycol(EG) at 300℃ was investigated over SiO2 and CeO2 supported Pt–Ni bimetallic catalysts prepared by incipient wetness impregnation methods. It was observed that impregnation sequence of Pt and Ni can affect the performance of catalysts apparently. Catalyst with Pt first and then Ni addition showed higher EG conversion and H2 yield owing to the Ni enrichment on the surface and the proper interaction between Pt and Ni. It was observed that although SiO2 supported catalysts exhibited better activity and H2 selectivity, CeO2 supported ones had better stability. This is attributed to the less coke formation on CeO2. Increasing Pt/Ni ratio enhanced the reaction activity, and Pt3–Ni7 catalysts with 3 wt% Pt and 7 wt% Ni showed the highest activity and stability. Ni surficial enrichment facilitated the C-C bond rupture and water gas shift reactions;and Pt addition inhibited methanation reaction. Electron transfer and hydrogen spillover from Pt to Ni suppressed carbon deposition. These combined effects lead to the excellent performance of Pt3–Ni7 supported catalysts.

Converting furfural residue wastes to carbon materials for high performance supercapacitor

Sustainable development based on the value-added utilization of furfural residues(FRs)is an effective way to achieve a profitable circular economy.This comprehensive work highlights the potential of FRs as precursor to prepare porous carbons for high performance supercapacitors(SCs).To improve the electrochemical performance of FR-based carbon materials,a facile route based on methanol pretreatment coupled with pre-carbonization and followed KOH activation is proposed.More defects could be obtained after methanol treatment,which is incline to optimize textural structure.The activated methanol treated FR-based carbon materials(AFRMs)possess high specific surface area(1753.5 m^(2) g^(-1)),large pore volume(0.85 cm^(3) g^(-1)),interconnected micro/mesoporous structure,which endow the AFRMs with good electrochemical performance in half-cell(326.1 F g^(-1) at 0.1 Ag^(-1),189.4 Fg^(-1) at 50 A g^(-1) in 6 mol L^(-1) KOH).The constructed symmetric SCs based on KOH,KOH–K_(3)Fe(CN)_(6) and KOH-KI electrolyte deliver energy density up to 8.9,9.9 and 10.6 Wh kg^(-1) with a capacitance retention of over 86%after 10,000 cycles.Furthermore,the self-discharge can be restrained by the addition of K_(3)Fe(CN)_(6) and KI in KOH electrolyte.This study provides an effective approach for high-valued utilization of FR waste.

Utilizing 3D DOSY NMR in the characterization of organic compounds in coal chemical wastewater

Coal chemical wastewater(CCW)with the features of high toxicity and poor biodegradability is a big issue in environmental remediation,posing a great threat to aquatic ecosystems and to human beings.Such complex molecular mixtures are notoriously difficult to characterize without initial physical separation.Herein,we present the 3D diffusion ordered spectroscopy(DOSY)analysis for CCW using DOSY-COSY and DOSY-HSQC methods,the advantages of this strategy have been demonstrated in the analysis of mixtures of aliphatic oxygenates and aromatic compounds,before being implemented on a genuine CCW sample in this study.The results showed that 3D DOSY is a robust and reliable tool for providing superior resolution and virtual separation of complex pollutants,and can be used as a general approach for structural elucidation.

NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue

Hydrothermal carbonization(HTC) is a valuable approach to convert furfural residue(FR) into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques(~1H and ^(13)C NMR,~1H-~1H COSY and ~1H-^(13)C HSQC etc.) especially 1D selective gradient total correlation spectroscopy(TOCSY NMR) were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions(180-240 ℃ at 8 h, and 1-24 h at 240 ℃) was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies.

NMR diffusion analysis of catalytic conversion mixtures from lignocellulose biomass using PSYCHE-iDOSY

The component analysis and structure characterization of complex mixtures of biomass conversion remain a challenging work.Hence,developing effective and easy to use techniques is necessary.Diffusion-ordered NMR spectroscopy(DOSY)is a non-selective and non-invasive method capable of achieving pseudo-separation and structure assignments of individual compounds from biomass mixtures by providing diffusion coefficients(D)of the components.However,the conventional 1H DOSY NMR is limited by crowded resonances when analyzing complex mixtures containing similar chemical structure resulting in similar coefficient.Herein we describe the application of an advanced diffusion NMR method,Pure Shift Yielded by CHirp Excitation DOSY(PSYCHE-iDOSY),which can record high-resolution signal diffusion spectra efficiently separating compounds in model and genuine mixture samples from cellulose,hemicellulose and lignin.Complicated sets of isomers(D-glucose/D-fructose/D-mannose and 1,2-/1,5-pentadiol),homologous compounds(ethylene glycol and 1,2-propylene glycol),model compounds of lignin,and a genuine reaction system(furfuryl alcohol hydrogenolysis with ring opening)were successfully separated in the diffusion dimension.The results show that the ultrahigh-resolution DOSY technique is capable of detecting and pseudo-separating the mixture components of C_(5)/C_(6) sugar conversion products and its derivative hydrogenation/hydrogenolysis from lignocellulose biomass.

Ternary deep eutectic solvents catalyzed D-glucosamine self-condensation to deoxyfructosazine: NMR study

Ternary deep eutectic solvents(TDESs) comprising choline chloride(Ch Cl), glycerol and L-arginine were synthesized as catalysts and solvents for the conversion of D-glucosamine(GlcNH_(2)) into deoxyfructosazine(DOF). The interactions between these three components in the prepared TDESs were studied by ^(1)H-,^(35)Cl-NMR spectra and ^(1)H diffusion-ordered spectroscopy(DOSY) measurements. The chemical shift changes of active hydrogen in the ^(1)H-NMR spectra of TDES system and widening of signals in the^(35)Cl-NMR spectra confirmed the hydrogen bonding interaction between the components, which was further supported by the decrease of diffusion coefficients(D) of the TDES components according to ^(1)H DOSY measurements. The influences of reaction temperature and L-arginine content in the TDESs on the yield of DOF were also studied. The experimental results have shown that when the molar ratio of Ch Cl, glycerol, and L-arginine was 1:2:0.1, DOF was the major product with a yield of 22.6% at 90℃ for 120 min. The chemical shift titration indicated that the carboxyl group of L-arginine in the TDES is the catalytical active site, so the mechanism of the catalytic reaction between Glc NH_(2) and the TDES was proposed. Moreover, a reaction intermediate, dihydrofructosazine, was identified in the self-condensation reaction of Glc NH_(2) by an in situ ^(1)H NMR technique.

Characterization of the acidity and basicity of green solvents by NMR techniques

The acidity and basicity of the solvents can influence the reaction outcome notably,and hence the precise measurement of pH is important for reaction.However,not all the pH values of organic solvents can be determined with a classic pH meter straightly.In this research,the acidity and basicity of environmentally friendly green solvents,such as ZnCl_(2) molten salt hydrate,ionic liquids(ILs)and deep eutectic solvents(DESs),were characterized by 31P and 1 H NMR spectroscopy using trimethylphosphine oxide(TMPO)and pyrrole as probe molecules at 298 K.For the ZnCl_(2) molten salt hydrate,the acidic strength of the ZnCl_(2) molten salt hydrate increased with the concentration of ZnCl_(2).By using the ^(1)H-pyrrole NMR approach,it was found that the base strength of amino acid-based ILs follows the order:[Ch][Lys]>[Ch][His].

Understanding the interaction mechanism of carbazole/anthracene with N,Ndimethylformamide:NMR study substantiated carbazole separation

Carbazole and anthracene,two aromatic hydrocarbon components contained in coal tar,are used as essential organic intermediates to synthesize various carbazole derivatives and anthraquinones.N,NDimethylformamide(DMF)is a commonly used solvent to extract carbazole from crude mixtures of carbazole and anthracene.However,the interaction between carbazole/anthracene and DMF in the extraction process is still to be fully understood at the molecular level.In this work,the intermolecular interaction of carbazole/anthracene with DMF was investigated using various NMR techniques,including 1 H NMR titration,variable temperature NMR spectroscopy(VT-NMR),Nuclear Overhauser Effect Spectroscopy(NOESY),and diffusion-ordered spectroscopy(DOSY).The observed 1 H chemical shift changes of carbazole indicated strong intermolecular hydrogen bonds between carbazole and DMF,which was further supported by the decrease in the molecular self-diffusion coefficients(D)of both carbazole and DMF according to DOSY measurements.Moreover,NOESY experiments revealed that the distance between the aldehydic hydrogen of DMF and the N–H of carbazole was smaller than 5Å.Accordingly,an intermolecular hydrogen bond between carbazole and DMF in the form of CO⋯H–N was proposed.This research increases our knowledge about the separation process of carbazole and anthracene and hence helps improve the methods.

热响应性阴阳离子表面活性剂混合体系囊泡的构筑与稳定性调控

制备稳定的表面活性剂囊泡是进一步发展囊泡技术的关键.本工作制备了两种酰胺基分别在疏水链和连接基团的阳离子Gemini表面活性剂(C_(12)A-C_(2)-AC_(2)和C_(2)-AC_(12)A-C_(2))与阴离子谷氨酸表面活性剂(C_(2)Glu)混合体系囊泡,系统研究了酰胺基位置和羧基间氢键对囊泡形成与热稳定性的影响.结果表明,位于疏水链上的酰胺基通过氢键可有效促进表面活性剂混合体系囊泡形成和热稳定性,C_(12)A-C_(2)-AC_(2)&C_(2)Glu囊泡在升高温度过程中保持蓝色乳光不变,但对于酰胺基位于连接基团上的C_(2)-AC_(12)A-C_(2)&C_(2)Glu囊泡溶液,其蓝色乳光随温度升高逐渐转变为乳白色或出现沉淀,降低温度溶液再次恢复蓝色乳光.含有两个羧基的C_(2)Glu的带电量及分子间氢键随p H此消彼长,p H 5.0时C_(2)Glu羧基形成的分子间氢键促进了C_(12)A-C_(2)-AC_(2)&C_(2)Glu和C_(2)-AC_(12)A-C_(2)&C_(2)Glu囊泡的形成和热稳定性,在升温过程中混合体系囊泡溶液均没有产生沉淀,而p H 10.0时这两个体系形成的囊泡溶液随温度升高分别出现蓝色乳光加深和沉淀现象.这类具有温度响应性、高效形成囊泡的体系具有重要的实际应用价值.

CircRNA expression profiles in decidual tissue of patients with early recurrent miscarriage

Circular RNAs(circRNAs)are a novel class of endogenous noncoding RNAs that play important roles in gene expression regulation.This study aimed to evaluate the potential role of circRNAs in decidual tissue of patients with early recurrent miscarriage(RM).We constructed circRNA expression profiles in decidual tissue using microarray data.A total of 123 differentially expressed circRNAs,including 78 upregulated and 45 downregulated circRNAs were detected in the early RM group compared with the control group(P<0.05).Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis also revealed the enrichment of specific circRNAs.The verified circRNA-targeted miRNA-mRNA network was constructed,most of the circRNAs harbored miRNA binding sites.The network involved 3 circRNAs,27 microRNAs and 82 mRNAs.Hsa_circRNA_103092-miR-224-PRLR network was selected to verify by qRT-PCR.These results showed that circRNAs are aberrantly expressed in the decidual tissue in early RM patients and play potential roles in the development of early RM.It gives new insights into the mechanism of recurrent miscarriage.

Functional characterization of disease/comorbidity-associated IncRNA

Background:Functional characterization of the long noncoding RNAs(IncRNAs)in disease attracts great attention,which results in a limited number of experimentally characterized IncRNAs.The major problems underlying the lack of experimental verifications are considered to come from the significant false-positive assignments and extensive genetic-heterogeneity of disease.These problems are even worse when it comes to the functional characterization in comorbidity(simultaneous/sequential presence of multiple diseases in a patient,and showing much wider prevalence,poorer treatment-response and longer illness-course than a single disease).Methods:Herein,FCCLnc was developed to characterize IncRNA function by(1)integrating diverse SNPs that were associated with 193 diseases standardized by International Classification of Diseases(ICD-11),(2)condition-specific expression of IncRNAs,(3)weighted correlation network of IncRNAs and protein-coding neighboring genes.Results:FCCLnc can characterize IncRNA function in both disease and comorbidity by not only controlling false discovery but also tolerating their disease heterogeneity.Moreover,FCCLnc can provide interactive visualization and full download of IncRNA-centered co-expression network.Conclusion:In summary,FCCLnc is unique in characterizing IncRNA function in diverse diseases and comorbidities and is highly expected to emerge to be an indispensable complement to other available tools.FCCLnc is accessible at https://idrblab.org/fcclnc/.