High Value-added Chemicals Research Articles

Ca promoted Ni–Co bimetallic catalyzed coal pyrolysis and char steam gasification

Coal catalytic pyrolysis has been applied in the clean and efficient utilization of low-rank coal to obtain combustible gases and high value-added chemicals. Herein, Ni–Co–Ca catalysts were added into coal through impregnation for catalytic pyrolysis of Yunnan lignite and the char steam gasification. The H2 production reached 3.24 mmol/g of coal and the gas conversion was 27.84% of the coal pyrolysis under 5Ni–5Co–1Ca. The char conversion reached 98.21% and the H2 production was 90.68 mmol/g of char steam gasification. Ni and Co could promote coal catalytic pyrolysis by cracking the C–H and C–C bonds. The formation of Ni–Co alloy could prevent catalysts inactivation due to the metal oxidation, lattice distortion and carbon deposition. Density functional theory (DFT) calculations indicated that the electron transfer from Co to Ni has been improved due to the Ca promoting effect, enhancing Ni catalytic activity and promoting coal pyrolysis for more small gaseous molecules. Ca could endow char with abundant pore structure, improving the irregular degree of char crystallite structure, which was attributed to the char gasification at high temperature to obtain H2. This study provided guidance to modulate pyrolysis products distribution by regulating catalysts properties.

The effect of glycerol additive on high value-added chemicals from tobacco waste pyrolysis

It is of significant importance to understand the role of glycerol additive for the improvement of the energy recovery during tobacco-waste pyrolysis. Utilizing ReaxFF-based molecular dynamic simulation, herein, we systematically studied the pyrolysis mechanism of tobacco with different concentrations of glycerol (5%, 10%, 16.5%, 20%, 25%) at different temperatures (1800 K, 2000 K, 2300 K, 2500 K, 2800 K). The calculation shows that a temperature of 2000 K is the optimal temperature for producing methanol and ethanol. Furthermore, the concentration of glycerol had a significant effect on promoting methanol production at high temperatures. Methanol's main generation pathway was influenced by temperature and glycerol concentration, while the primary pathway of ethanol production was independent of them. Moreover, a pyrolysis reaction framework was created for methanol and ethanol production, and their main formation reactions were validated. Finally, a chemical kinetic analysis of the pyrolysis process confirmed the accuracy of the ReaxFF MD simulations.

Selective two-electron electrocatalytic conversion of 5-Hydroxymethylfurfural boosting hydrogen production under neutral condition over Co(OH)2-CeO2 catalyst

The coupling of electrocatalytic oxidation of biomass derivatives with hydrogen evolution reaction (HER) is a promising strategy to promote hydrogen production, but it is extremely challenging to control the mild electrocatalytic conversion of biomass to high value-added chemicals simultaneously. A Co(OH)2-CeO2 self-supported catalyst is constructed and used as anode for selective electrocatalytic conversion of biomass derivative 5-hydroxymethylfurfural (HMF) coupled with HER in two-chamber electrolysis system. The adjusting of pH and potential regulates the oxidation ability of hydroxyl and aldehyde groups, achieving selective two-electron electrocatalytic conversion of HMF to 2-furancarboxylic acid (HMFCA) with a selectivity of 89.4%. In situ Raman spectroscopy reveals that the evolution of Co multivalent active species at different electrolysis conditions is key to the selective oxidation of HMF. In addition, the hydrogen production coupled with selective electrocatalytic conversion of HMF is 4.1 times that of the water splitting system, revealing its potential in developing clean energy.

Ultrastable Cu-Based Dual-Channel Heterowire for the Switchable Electro-/Photocatalytic Reduction of CO2.

Catalytic conversion of CO2 into high value-added chemicals using renewable energy is an attractive strategy for the management of CO2 . However, achieving both efficiency and product selectivity remains a great challenge. Herein, a brand-new family of 1D dual-channel heterowires, Cu NWs@MOFs are constructed by coating metal-organic frameworks (MOFs) on Cu nanowires (Cu NWs) for electro-/photocatalytic CO2 reductions, where Cu NWs act as an electron channel to directionally transmit electrons, and the MOF cover acts as a molecule/photon channel to control the products and/or undertake photoelectric conversion. Through changing the type of MOF cover, the 1D heterowire is switched between electrocatalyst and photocatalyst for the reduction of CO2 with excellent selectivity, adjustable products, and the highest stability among the Cu-based CO2 RR catalysts, which leads to heterometallic MOF covered 1D composite, and especially the first 1D/1D-type Mott-Schottky heterojunction. Considering the diversity of MOF materials, the ultrastable heterowires offer a highly promising and feasible solution for CO2 reduction.

Catalytic conversion of biomass


 Resource scarcity and increasing climate change have brought attention to the need for sustainable and renewable resources. Biomass is an earth-rich material with great potential as a feedstock for alternative fuels and chemicals. In order to utilize biomass efficiently, such biopolymers must be depolymerized and converted into key structural units and/or target products, and biological or chemical catalysts are often used for fast and energy-efficient reactions. This paper presents recent advances in the catalytic conversion of biomass into biofuels and value-added products. Hydrodeoxygenation is an important and unique method for converting biomass and biomass-derived oxygenated chemicals into high value-added chemicals and fuels. However, the synthesis of catalysts with excellent hydrogenation and hydrodeoxygenation performance at the same time remains a great challenge.

Solar-driven dry reforming of methane using RuNi single-atom alloy catalyst coupled with thermal decomposition of carbonates

Traditional industries, which usually involve the thermal decomposition of carbonates into metal oxide, give a great contribution to the production of carbon dioxide (CO2). Dry reforming of methane (DRM) is a process that transforms the greenhouse gases CO2 and CH4 into syngas (CO and H2), providing an efficient method for the usage of CO2 and the creation of high value-added chemicals. However, such traditional process typically requires high temperature and pressure to break the CO and CH bond, resulting in high operating costs. The development of solar-driven catalysis for the DRM is crucial to the search for a more sustainable path. Herein, RuNi single-atom alloy (RuNi-SAA) supported on Al2O3 was synthesized and exhibited enhanced production rates of H2 and CO (8.98 and 10.70 mmol·g−1·min−1, respectively) under photothermal condition. Additionally, CO2-emitting carbonates thermal decomposition reaction in traditional industries was combined with CO2-consuming DRM reaction to reduce CO2 emission. The selectivity of CO2 can be significantly reduced from 100% (direct carbonates thermal decomposition) to 20%, with simultaneously producing H2 and CO (0.68 and 0.44 mmol·g−1·min−1). This study presents an effective strategy to construct highly reactive SAA catalysts for photothermal DRM reaction and offers an alternative method to utilize and directly convert CO2 in traditional industries for the manufacture of high value-added chemicals.

Mechanisms of biochar-mediated promotion of acidogenic fermentation in waste activated sludge and propionic acid production pathways

The conversion of organic matter in waste activated sludge (WAS) into high value-added chemicals of volatile fatty acids (VFAs) has become a focus of attention worldwide. However, the conversion of WAS to a certain acid among VFAs is difficult. Herein, for the first time, biochar was used to promote sludge solubilization, hydrolysis and acidogenic fermentation for the production of propionic acid. The results illustrated that biochar (prepared at 450 °C, containing environmental persistent free radicals (EPFRs) of 15.91 × 1015 spins/g) stimulated sludge solubilization, hydrolysis and VFAs production, enhancing sludge cell lysis rate, VFAs production, propionic acid ratio, protease, α-glucosidase and nicotinamide adenine dinucleotide hydrogen (NADH)/nicotinamide adenine dinucleotide (NAD+) ratio by 10.53 %, 107.42 %, 17.52 %, 68 %, 32 % and 76.10 % respectively, compared with those observed in the control group without biochar addition. And once the EPFRs were shielded, they decreased. The signal of EPFRs decreased from 15.91 × 1015 spins/g to 15.20 × 1015 spins/g on day 2 and 8.50 × 1015 spins/g on day 4. The EPFRs contained in the biochar played an important role in the intermediary function and interfered with the bacterial metabolic pathways. Metagenomics sequencing also revealed that biochar EPFRs promoted the sludge acidogenic fermentation to produce propionic acid ([EC:7.1.1.2]) and partly inhibited acetic acid production ([EC:1.2.1.3]). This study reveals that biochar could promote sludge solubilization, hydrolysis and promote propionic acid production, which could be used as a new strategy for acid production in the future.

Critical role of support crystal structures on highly selective hydrodeoxygenation of lignin-derived vanillin over Pd/ZrO2 catalysts

Hydrodeoxygenation (HDO) of bio-oils obtained by rapid pyrolysis of biomass into high value-added chemicals generally required harsh conditions. Herein, three kinds of mixed-phase ZrO2 supports (denoted as ZSX, X = 2–4) with different crystal structure proportions were prepared by one-pot hydrothermal synthesis method, and their performance on the properties of Pd/ZrO2 catalysts were investigated for vanillin HDO. Pd/ZS3 exhibited excellent efficiency in HDO of vanillin, a typical model compound of lignin, achieving approximately 100% yield of 2-methoxy-4-methylphenol (MMP) in presence of n-butanol as solvent and polymethyl hydrogen siloxane (PMHS) as hydrogen donor under mild conditions (35 °C, 1 h). It was due to catalytic synergy of exposed metal active sites, oxygen vacancies (Ov) and acid sites to occur electron transfer and enhance interaction between Pd and ZrO2. By tuning the crystal structure of ZrO2 support, the influence of Ov and acid sites of Pd/ZrO2 over vanillin HDO performance was investigated, Pd/ZS2 with abundant Ov and Pd/ZS4 with substantial acid sites promoted hydrogenation and hydrogenolysis, respectively, Pd/ZS3 possessed preferable conversion and selectivity as having the properties of both at once. Additionally, reaction pathway was also proposed in which vanillin was converted to MMP by combining intermediate of 4-hydroxy-methyl-2-methoxyphenol (HMP) with active hydrogen species while removing water. This developed catalysts with different crystalline highlighted an enormous promise for HDO of bio-oils into green fuel under mild conditions.

Mass Spectrometric Evaluation of the Catalytic Deoxygenation of Soluble Organic Matter in Xiaolongtan Lignite

The organic matter in Xiaolongtan lignite was thermally dissolved by cyclohexane, methanol and isopropanol (2-propanol) in sequence to obtain thermal dissolution (TD) extracts. Co-Mo/γ-Al2O3 was used as the catalyst for the catalytic hydrogenation of TD extracts to remove oxygen. Both TD extracts and the corresponding catalytic products were analyzed by the combination of gas chromatography/mass spectrometry (GC/MS) and Orbitrap MS to reveal more molecular details. GC/MS analysis shows that cyclohexane can extract low polar organic matter in coal, while methanol and isopropanol as nucleophilic reagents can break C-O bonds in coal, thus removing oxygen. Catalyst can trigger the fracture of alkyl chains and the activation of H2, thus promoting the removal of oxygen atom and the generation of aromatics. Double bond equivalent (DBE) value and carbon number (CN) were obtained through Orbitrap MS data. The decrease of both DBE and CN after catalytic conversion indicates the breaking of bridged bonds. The introduction of various MS systems provides an effective analytical tool for studying the catalytic deoxidation of lignite, thereby guiding the conversion of lignite to clean liquid fuels and high value-added chemicals. Co-Mo/ γ- Al2O3 catalysts activates H2 to H⋯H, which further splits into H+ and H−. H⋯H deoxygenates by hydrogenating C=C bond, attacking C-O bond or directly attacking oxygen atom. H+ will preferentially attack oxygen atom with high electronegativity, and break Cal-O bridge bond to achieve deoxygenation, thus reducing the relative abundance of oxygen containing compounds.

Synthesis of aromatic monomers via hydrogenolysis of lignin over nickel catalyst supported on nitrogen-doped carbon nanotubes

The utilization of lignin to produce high value-added chemicals remains a significant challenge, this study reports the synthesis of highly active nitrogen-doped carbon nanotubes to support nickel-based catalysts via a two-stage pyrolysis process using a mixture of melamine and nickel acetate. The catalyst morphology is controlled through the use of melamine, the doped pyridinic nitrogen serves as an anchoring site for Ni metal, facilitating the dispersion of Ni metal and the formed Ni-Nx bond enhanced the stability of the catalyst. Additionally, the electron transfer between Ni and N atoms promoting the activation of hydrogen on the metallic nickel surface, which together with the aforementioned factors, contributes to the cleavage of the C-O bond in lignin, with 23.1% monomer yield under mild conditions. The density functional theory (DFT) calculations reveal that doped nitrogen atoms can provide electrons to carbon atoms, resulting in an electron-rich state that facilitated the adsorption of hydrogen.

Selective peroxidation of isobutane with molecular oxygen over molybdenum oxide catalyst for direct synthesis of di-tert-butyl peroxide

The direct conversion of isobutane to high value-added chemicals is important for utilization of C4 hydrocarbon resources. This work proposed a novel route of isobutane peroxidation with molecular oxygen for green synthesis of di-tert-butyl peroxide (DTBP), widely used as polymerization initiating/crosslinking agent and diesel additive. For the first time, MoO3 was demonstrated as selective catalyst for isobutane peroxidation to DTBP. The results indicated that, the reactivity depended on the oxygen adsorption capacity of MoO3 catalyst, and the selectivity to DTBP was determined by the amount of surface Mo = O sites. During the reaction, tert-butyl hydroperoxide (TBHP) was generated from isobutane peroxidation as intermediate product, and subsequently converted to DTBP on Mo = O active sites. Under the optimized conditions, a high oxygen conversion (>95%) and stable product selectivities (DTBP ∼ 20 wt%, TBHP ∼ 13 wt%) were obtained during continuous catalyst re-usage runs. This work provides an environmental route for both C4 hydrocarbon utilization and DTBP production.

Designing TM-N2O2Cx single-atom catalysts for electrocatalytic CO2 reduction

Electrocatalytic CO2 reduction reaction (CO2RR) has been extensively considered as a potential carbon cycle technology because it can use CO2 as resources to produce high value-added fuels and chemicals under mild conditions. Therefore, developing highly efficient CO2RR catalysts is extremely significant. Here, we designed a series of TM-N2O2Cx (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) single-atom catalysts and investigated their catalytic activities for CO2RR by using the density functional theory. Interestingly, these TM-N2O2Cx catalysts exhibit excellent CO2RR selectivity towards three kinds of different products, including CH4, CO, and HCOOH at relatively low overpotentials, where the CO2RR product of Sc-N2O2Cx, Mn-N2O2Cx, and Zn-N2O2Cx is CO, and that of V-N2O2Cx is CH4, while the other six catalysts would produce HCOOH. Moreover, the best pathway for CH4 formation is also unveiled, that is, * + CO2 → C*OOH → C*O + H2O → C*HO → C*HOH → C*H + H2O → C*H2 → C*H3 → * + CH4. In short, TM-N2O2Cx catalysts exhibit high catalytic activity for electrocatalytic CO2RR, which provides useful information for experimental scientists to synthesize these promising CO2RR catalysts.

Solvent- and Co-Catalyst-Free Cycloaddition of Carbon Dioxide and Epoxides Catalyzed by Recyclable Bifunctional Niobium Complexes.

CO2, as a cheap and abundant renewable C1 resource, can be used to synthesize high value-added chemicals. In this paper, a series of bifunctional metallic niobium complexes were synthesized and their structures were characterized by IR, NMR and elemental analysis. All of these complexes have been proved to be efficient catalysts for the coupling reaction of CO2 and epoxides to obtain cyclic carbonates under solvent- and co-catalyst-free conditions. By using CO2 and propylene oxide as a model reaction, the optimal reaction conditions were systematically screened as: 100 °C, 1 MPa, 2 h, ratio of catalyst to alkylene oxide 1:100. Under the optimal reaction conditions, the bifunctional niobium catalysts can efficiently catalyze the coupling reaction with high yield and excellent selectivity (maximum yield of >99% at high pressure and 96.8% at atmospheric pressure). Moreover, this series of catalysts can also catalyze the coupling reaction at atmospheric pressure and most of them showed high conversion of epoxide. The catalysts have good substrate suitability and are also applicable to a variety of epoxides including diepoxides and good catalytic performances were achieved for producing the corresponding cyclic carbonates in most cases. Furthermore, the catalysts can be easily recovered by simple filtration and reused for at least five times without obvious loss of catalytic activity and selectivity. Kinetic studies were carried out preliminarily for the bifunctional niobium complexes with different halogen ions (3a(Cl-), 3b(Br-), 3c(I-)) and the formation activation energies (Ea) of cyclic carbonates were obtained. The order of apparent activation energy Ea is 3a (96.2 kJ/mol) > 3b (68.2 kJ/mol) > 3c (37.4 kJ/mol). Finally, a possible reaction mechanism is proposed.

Rational engineering of multifunctional ionic covalent organic frameworks for metal-free and efficient chemical fixation of CO2 under mild conditions

The transformation of CO2 into high value-added chemicals such as cyclic carbonates provide a promising technology to solve the exceeding CO2 emission. In the absence of solvent and co-catalyst, the development of highly efficient and recyclable metal-free catalyst with excellent performance under mild conditions still remains a great challenge. Herein, a series of multifunctional ionic covalent organic frameworks (COFs) was synthesized via post-synthesis modification strategy of covalently grafting functionalized imidazole on triazine-based COF skeleton. The influence of bridged alkyl chain, imidazole functional group, nucleophile and grafting amount on catalytic activity was investigated in the cycloaddition of CO2 with epichlorohydrin. Remarkably, IM-COF-Br-Vinyl could afford 96.49% yield and > 99% selectivity with a turnover frequency (TOF) value of 5434 h−1 at 0.5 MPa CO2 pressure and 100 ℃ for 6 h, which was superior to other reported COF catalysts. The excellent catalytic performance was mainly ascribed to its excellent CO2 adsorption capacity and the synergistic effect of CO2-philic basic sites, hydrogen bond donors and nucleophilic anions. Additionally, the reusability and versatility of the catalyst was considered and the proposal catalytic mechanism was speculated according to the above conclusions. This strategy not only avoided the environmental pollution caused by catalytic system itself but also ensured the safety and low-energy consumption by realizing highly efficient catalytic conversion of CO2 under mild conditions. This provides an effective avenue for the design and synthesis of ionic liquid functionalized COF catalysts and the development of CO2 activation and utilization.

Unveiling the complementary mechanism in the one-pot synthesis of glycerol carbonate from CO2 and glycerol

The chemical conversion of inert carbon dioxide (CO2) into high value-added chemicals is a continuing challenge. In this work, an experimental and theoretical mechanism study is presented for one-pot synthesis of glycerol carbonate (GC) from CO2, glycerol (Gly), and propylene epoxide (PO) catalyzed by 1,8-diazabicyclo[5.4.0]undec-7-enenium iodide (HDBUI) ionic liquid. 92% GC yield was obtained in the one-pot reaction through cycloaddition of CO2 with PO to produce propylene carbonate (PC), followed by transesterification of Gly with PC to yield targeted products. Density functional theory (DFT) calculations were used to unveil the HDBUI-mediated catalytic mechanism and key catalytic species. It was revealed that the HDBUI-catalyzed cycloaddition was assisted by the hydrogen bond donor Gly, the transesterification reactant, by promoting the ring-opening of PO and the insertion of CO2. By activating Gly hydroxyl group, alkaline HDBUI-bonded propan-1-ylium-2-yl carbonate, an intermediate in cycloaddition, catalyzed transesterification. The complementary mechanism of cycloaddition and transesterification in the one-pot provides a feasible method for utilizing inert CO2.

Highly Efficient Ruthenium-Catalyzed Semi-hydrogenation of Urea Derivatives to Formamides.

The utilization of CO2 as a non-toxic and cheap feedstock for C1 is a desirable route to achieve high value-added chemicals. In this context, we report a highly efficient ruthenium-catalyzed semi-hydrogenation reaction of CO2 -derived ureas. Various alkyl and aryl urea derivatives were successfully hydrogenated to obtain the corresponding recyclable amines and formamides (up to 97 % yield), highlighting the good substrate applicability of this method, which makes this method a sustainable alternative for the hydrogenation of CO2 to formamides in the presence of amines. In the meantime, we have discovered a new pathway that enables rapid hydrogenation of urea derivatives even at lower H2 pressure (<5 bar). This methodology might provide a new insight into the reduction functionalization of CO2 under mild pressure to form new C-N bond. Based on the control experiments and the observed intermediate products, we clarify the mechanism for selective semi-hydrogenation of ureas.

Fe-Ni bimetallic nanoparticles encapsulated into nanofibrous carbon microspheres as a catalytic nanoreactor for highly selective hydrogenation of 5-hydroxymethylfurfural to 2,5-dihydroxymethylfuran or 2,5-dihydroxymethyltetrahydrofuran

BackgroundThe highly efficient conversion of renewable biomass-derived platform compounds to high value-added chemicals is one of the most promising solution to the current rapid consumption of fossil resources. MethodsNanofibrous and porous carbon microspheres (NPCMs) were developed from chitin biomass and used to encapsulate Fe-Ni bimetallic nanoparticles for the formation of a novel catalytic nanoreactor (Fe-Ni/NPCMs), which was then used for the selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfuran (DHMF) or 2,5-dihydroxymethyltetrahydrofuran (DHMTHF). Significant findingsThe NPCMs consisted of N-doped carbon nanofibers with a high surface area. The Fe-Ni bimetallic nanoparticles were uniformly dispersed on the carbon nanofiber surfaces of the Fe-Ni/NPCMs, resulting in abundant catalytic sites and excellent catalytic performance. Importantly, the Fe-Ni/NPCMs showed highly-selective hydrogenation of HMF to DHMF or DHMTHF with high yields of 93.6% or 94.9% through simply modulating the reaction conditions. Increasing the zero valent iron (Fe0) content in the Fe-Ni/NPCMs significantly promoted the DHMTH selectivity from HMF hydrogenation. Moreover, the Fe-Ni/NPCMs presented high stability and recyclability, and thus they are applicable to other biomass conversions. Therefore, Fe-Ni/NPCMs have promising industrial application in the production of high value-added chemicals from biomass-derived feed-stocks.

Direct Conversion of CO2 in Lime Kiln Waste Gas Catalyzed by a Copper-Based N-heterocyclic Carbene Porous Polymer.

Industrial waste gas is one of the major sources of atmospheric CO2 , yet the direct conversion of the low concentrations of CO2 in waste gases into high value-added chemicals have been a great challenge. Herein, a copper-based N-heterocyclic carbene porous polymer catalyst (Cu@NHC-1) for the direct conversion of low concentration CO2 into oxazolidinones was successfully fabricated via a facile copolymerization process followed by the complexation with Cu(OAc)2 . A continuous flow device was designed to deliver a continuous and stable carbon source for the reaction. Due to the triple synergistic effect of its porous structure, nitrogen activation sites and catalytic Cu center, Cu@NHC-1 shows highly efficient and selective adsorption, activation, and conversion of the low concentration CO2 (30 vol%). Its practical application potential is demonstrated by the ability to successfully convert the CO2 in lime kiln waste gas into oxazolidinones in satisfactory yields under mild conditions.

Base-free selective oxidation of monosaccharide into sugar acid by surface-functionalized carbon nanotube composites

Selective oxidation of biomass-derived monosaccharide into high value-added chemicals is highly desirable from sustainability perspectives. Herein, we demonstrate a surface-functionalized carbon nanotube-supported gold (Au/CNT-O and Au/CNT-N) catalyst for base-free oxidation of monosaccharide into sugar acid. Au/CNT-O and Au/CNT-N surfaces successfully introduced oxygen- and nitrogen-containing functional groups, respectively. The highest yields of gluconic acid and xylonic acid were 93.3% and 94.3%, respectively, using Au/CNT-N at 90 °C for 240 min, which is higher than that of using Au/CNT-O. The rate constants for monosaccharide decomposition and sugar acid formation in Au/CNT-N system were higher, while the corresponding activation energy was lower than in Au/CNT-O system. DFT calculation revealed that the mechanism of glucose oxidation to gluconic acid involves the adsorption and activation of O2, adsorption of glucose, dissociation of the formyl C-H bond and formation of O-H bond, and formation and desorption of gluconic acid. The activation energy barrier for the glucose oxidation over Au/CNT-N is lower than that of Au/CNT-O. The nitrogen-containing functional groups are more beneficial for accelerating monosaccharide oxidation and enhancing sugar acid selectivity than oxygen-containing functional groups. This work presents a useful guidance for designing and developing highly active catalysts for producing high-value-added chemicals from biomass.

Urea impregnation into fungus pretreated corn stover to perform pyrolysis for production of nitrogen-containing bio-oil and nitrogen-doped biochar

Urea was introduced into the fungal pretreated corn stover and then the urea soaked materials were subjected to pyrolysis for the production of nitrogen-containing bio-oil and nitrogen-doped biochar. The urea soaking effectively realized the enrichment of nitrogen-containing compounds in the bio-oil and the maximal content of the nitrogen-containing compounds in bio-oils reached up to 66.32% under 4 wt% urea concentration. Among the nitrogen-containing compounds, amines were the most dominant component with the maximal content of 41.17%. The higher urea concentration is beneficial to make more nitrogen be fixed in the biochar. The nitrogen content of the biochar reached up to 12.86 wt% under 8 wt% urea concentration. Nitrogen on the biochar surface existed in the form of pyrrolic-N, pyridinic-N and graphite-N. In conclusion, urea simple soak on fungus pretreated biomass to perform pyrolysis is a promising approach to obtain high value-added nitrogen-containing chemicals and nitrogen-doped biochar with high nitrogen content.