Incorporation of Nanocatalysts for the Production of Bio-Oil from Staphylea holocarpa Wood

Biomass has been recognized as the most common source of renewable energy. In recent years, researchers have paved the way for a search for suitable biomass resources to replace traditional fossil fuel energy and provide high energy output. Although there are plenty of studies of biomass as good biomaterials, there is little detailed information about Staphylea holocarpa wood (S. holocarpa) as a potential bio-oil material. The purpose of this study is to explore the potential of S. holocarpa wood as a bio-oil. Nanocatalyst cobalt (II) oxide (Co3O4) and Nickel (II) oxide (NiO) were used to improve the production of bio-oil from S. holocarpa wood. The preparation of biofuels and the extraction of bioactive drugs were performed by the rapid gasification of nanocatalysts. The result indicated that the abundant chemical components detected in the S. holocarpa wood extract could be used in biomedicine, cosmetics, and biofuels, and have a broad industrial application prospect. In addition, nanocatalyst cobalt tetraoxide (Co3O4) could improve the catalytic cracking of S. holocarpa wood and generate more bioactive molecules at high temperature, which is conducive to the utilization and development of S. holocarpa wood as biomass. This is the first time that S. holocarpa wood was used in combination with nanocatalysts. In the future, nanocatalysts can be used to solve the problem of sustainable development of biological resources.


Introduction
One of the sustainable development goals of the United Nations 2030 agenda is to ensure access to affordable, reliable, and sustainable energy. Increasing the use of renewables in the global energy landscape is essential. Biomass is a substance formed by the metabolism of organisms that are usually derived from plants, industry, or agricultural and forestry wastes [1][2][3]. It can be a source of each energy treatment stage, especially for wood. Wood biomass is primarily intended for sustainable energy, fully integrating forestry and timber sectors [4][5][6]. Bioenergy-based production of biomass resources is gaining global attention, as it plays a critical role as an essential substitute for fossil energy [7][8][9]. Studies reported that biomass can serve as a good sustainable resource in the textile manufacturing field [10,11]. Biomass energy is currently being analyzed globally and formulate policy measures [12,13]. There is plenty of evidence that biomass wastes are suitable sources for bioenergy materials [14][15][16][17].
In many European countries, selected woody crops are used as raw materials for industrial and energy applications of biomass energy [18]. Forest biomass energy resources show great value and potential as important sustainable energy and renewable sources [19,20]. The use of bioenergy to develop renewable and clean biofuels can help to alleviate the worsening world energy crisis [21,22]. Crude bio-oil can also be produced in the process of thermochemical conversion of biomass and may contain different types of compounds, such as lignin-derived oligomers, alcohols, phenols, and aldehydes. So far, crude biooil has been used for wood fragrances, biodegradable polymers, resins, and fuel oil for S. holocarpa Wood (5 g)+NiO (0.025 g)+Co 3 O 4 (0.025 g)

Solvent Extractive
About 10 g of S. holocarpa wood powder was extracted with 20 mL of solvents, as mentioned in Table 1a. The pure extractive was obtained after a series of Soxhlet extraction processes as cited. The extractives were examined with FTIR, GC-MS analysis, and LC-QTOF-MS analysis.
FTIR analysis was performed using the Nicolet iS10 (Thermo Fisher, Waltham, MA, USA) instrument. A thin potassium bromide (KBr) disk was prepared from a mixture of KBr and the catalyst-wood samples at a ratio of 70:1 using mortar and pestle. The KBr disk was then loaded into an FTIR spectrophotometer at wavelengths from 400 cm −1 to 4000 cm −1 for 64 scans.
GS-MS analysis was analyzed with GC-MS (Agilent 7890B-5977A, Santa Clara, CA, USA). A HP-5MS column (30 mm × 250 µm × 0.25 µm) and an elastic quartz capillary column were used, along with a carrier gas of high-purity helium at a flow rate of 1 mL/min and a split ratio of 2:1. The temperature program for GC started at 50 • C and increased to 250 • C at a rate of 8 • C/min, followed by a further increase to 280 • C at a rate of 5 • C/min. The entire MS program scanned for a mass range of 30-600 amu with an ionization voltage of 70 eV and an ionization current of 150 µA. The ion source and quadrupole temperatures were set to 230 and 150 • C, respectively.

The Physicochemical Properties of the Catalyst-Wood Mixture
The physicochemical properties of the catalyst-wood mixture (Table 1b) were examined with three main analyses: TGA, TGA-FTIR, and PY/GC-MS. TGA analysis was performed using a thermogravimetric analyzer (TG-Q50, TA Instruments, New Castle, DE, USA). The analysis settings were as follows: nitrogen gas (N 2 ) as a carrier gas with a 60 mL/min release rate. Temperature optimization was performed in four settings: 750 • C, 60 • C/min; 850 • C, 60 • C/min; 950 • C, 20 • C/min; and 950 • C, 100 • C/min. The TG and DTG curves were obtained and compared for thermal stability in order to study the rate of change of mass of S. holocarpa wood samples.
TGA-FTIR analysis was analyzed by a combined TGA-FTIR analyzer (TG-Q500, TGA Instruments, New Castle, DE, USA with FTIR-Thermo Scientific Nicolet iS10, USA). The analysis settings were as follows: nitrogen gas (N 2 ) as a carrier gas with a 60 mL/min release rate; temperature increase from room temperature to 950 • C at 5 • C/min. Threedimensional (3D) TG-FTIR spectra were generated for the study on the pyrolysis volatiles and structures.
PY/GC-MS analysis was conducted with a PY/GC-MS spectrometer (CDS 5000-Agilent 7890B-5977A). The sample was pyrolyzed at 950 • C with a heating rate of 20 • C/MS. The gas produced in the pyrolysis process was then injected in the GC-MS analyzer. The analysis settings for the GC-MS were as follows: TR-5MS column with a capillary size of 0.25 µm × 0.25 mm × 30 m at a 28-500 amu scanning range; shunt rate at 50 mL/min; split ratio at 50:1; temperature setting in two stages (increase rate of 5 • C/min from 40-120 • C and increase rate of 10 • C/min from 120-200 • C). Multiple components detected by the PY/GC-MS were categorized into four groups aldehydes and ketones, acids and esters, alcohols and ethers, and hydrocarbons for better understanding and analysis of the pyrolysis by products.

Results and Discussion
3.1. Extractive of S. holocarpa 3.1.1. Analysis of FTIR All spectra showed a typical lignin mode, and the characteristic absorption peaks of lignin were 1646, 1456, 1403, and 1323 cm −1 (Figure 1 and Table 2). The main structure of lignin was very similar to the characteristic band of the functional group. There was no significant change at 1273, 1081, 1046, or 878 cm −1 , and S. holocarpa (methanol) was also weakened at 2980 cm −1 of cellulose, indicating that cellulose lignin was extracted [37]. The latter part was hydrolyzed [38]. Except for the different infrared absorption intensities all spectra were similar; the most typical band (1640 cm −1 ) represents the aromatic region of lignin [39,40]. In Figure 1, except for the peaks at 3446 and 1081 cm −1 , the transmission intensities of all the peaks exceeded other values. As the carbon species changed, the transmission intensities of all peaks gradually decreased, indicating that these groups contained less carbon. There were mainly OH stretch at the peak of 3446 cm −1 , -CH stretch at the peak of 2980 cm −1 , C=C stretch at the peak of 1646 cm −1 , CH stretch at the peak of 1456 cm −1 , and CC stretching vibration at the peak of 1270 cm −1 . The peak of 1046 cm −1 shows CO stretching. The 3742-2980, 2980-2863, and 1646-878 cm −1 ranges were the main concentrated parts of the absorption peaks of the three extract samples.  S. holocarpa wood's methanol, benzene/ethanol and ethanol/methanol three extracts of light transmittance have changed in different degrees. The results showed that the main organic chemical components were ketones, acids, ethers, and so on [41]. In particular, the structure containing O and fat almost disappeared, which in turn showed that the intensity of the absorption peaks in the corresponding band weakened to varying degrees. The change in the functional group reflected the oxidation reaction activity of S. holocarpa wood to a certain extent. In addition, the characteristic absorption peak (1000-690 cm −1 ) indicated that ether, benzene, phenol, alcohol, and acid were partly extracted ( Figure 1). From the FTIR results, it can be seen that all three samples contained mixtures with complex organic components and extremely high levels of oxygen. This included ether, carboxylic acids, aromatic rings, and other oxygen-containing organic substances (Table 2).  S. holocarpa wood's methanol, benzene/ethanol and ethanol/methanol three extracts of light transmittance have changed in different degrees. The results showed that the main organic chemical components were ketones, acids, ethers, and so on [41]. In particular, the structure containing O and fat almost disappeared, which in turn showed that the intensity of the absorption peaks in the corresponding band weakened to varying degrees. The change in the functional group reflected the oxidation reaction activity of S. holocarpa wood to a certain extent. In addition, the characteristic absorption peak (1000-690 cm −1 ) indicated that ether, benzene, phenol, alcohol, and acid were partly extracted ( Figure 1). From the FTIR results, it can be seen that all three samples contained mixtures with complex organic components and extremely high levels of oxygen. This included ether, carboxylic acids, aromatic rings, and other oxygen-containing organic substances (Table 2). These components are also the main chemical components of biomass.
Interestingly, compound n-hexadecanoic acid was detected in high abundance in all three solvent types (Figure 2a-c). It has anti-inflammatory properties and used to treat rheumatic symptoms [48] Adventitious roots cultured in vitro contained two valuable biologically active compounds: isosorbide and n-hexadecanoic acid [49]. Compound 1-Hexanol, 2-ethyl was detectable in all three solvent types and showed highest abundance in the S. holocarpa (benzene/ethanol) extractive ( Figure 2b). It is widely used for the production of petroleum additives, plasticizers, and ore dressings, as well as printing and dyeing for paints and films [50][51][52].
There were some other medicinally important compounds detected in the S. holocarpa wood extract, such as dihydroxyacetone, clindamycin, thymol, trimethoorim-supamethoxazole, and D-mannose. Dihydroxyacetone can be used to synthesize medicines for the treatment of cardiovascular diseases [53]. It can also be used in cosmetics to prevent excessive evaporation of skin moisture and to protect against ultraviolet radiation [54,55]. Clindamycin is a lincomycin antibacterial drug [56]. Clindamycin and Trimethoprim-Sulfamethoxazole provide a significant increase in resistance to s-aureus infection in children [57]. Thymol has antibacterial and antifungal effects [58] as well as neuroprotective effects [59]. D-Mannose regulates T cells and inhibits immunopathology [60,61].
With detailed analysis of the detected compounds, it can be seen that S. holocarpa wood contains many healthy and beneficial chemical components. The beneficial compounds in the extract could be useful in a wide range of industrial applications, such as biomedical, cosmetic, and food products. This study could provide scientific foundation for the research and development of S. holocarpa wood. The active chemical composition of S. holocarpa (methanol) is (Z,Z)-9,12-Octadecadienoic acid, which had the highest abundance of density ( Figure 2a). The (Z,Z)-9,12-Octadecadienoic acid was produced from linoleic acid via expression of fully recombinant E. coli cells from the diol synthase of Aspergillus nidulans [42,43]. Compound maltol is a commonly used food additive, and studies reported that maltol is preventative for liver oxidative damage caused by alcohol [44,45]. The ruthenium cyme complex derived from maltol has antitumor properties [46], and maltol can treat inflammatory-bowel-disease patients with iron-deficiency anemia [47].
Interestingly, compound n-hexadecanoic acid was detected in high abundance in all three solvent types (Figure 2a-c). It has anti-inflammatory properties and used to treat rheumatic symptoms [48] Adventitious roots cultured in vitro contained two valuable biologically active compounds: isosorbide and n-hexadecanoic acid [49]. Compound 1-Hexanol, 2-ethyl was detectable in all three solvent types and showed highest abundance in the S. holocarpa (benzene/ethanol) extractive ( Figure 2b). It is widely used for the production of petroleum additives, plasticizers, and ore dressings, as well as printing and dyeing for paints and films [50][51][52].
There were some other medicinally important compounds detected in the S. holocarpa wood extract, such as dihydroxyacetone, clindamycin, thymol, trimethoorim-supamethoxazole, and D-mannose. Dihydroxyacetone can be used to synthesize medicines for the treatment of cardiovascular diseases [53]. It can also be used in cosmetics to prevent excessive evaporation of skin moisture and to protect against ultraviolet radiation [54,55]. Clindamycin is a lincomycin antibacterial drug [56]. Clindamycin and Trimethoprim-Sulfamethoxazole provide a significant increase in resistance to s-aureus infection in children [57]. Thymol has antibacterial and antifungal effects [58] as well as neuroprotective effects [59]. D-Mannose regulates T cells and inhibits immunopathology [60,61].
With detailed analysis of the detected compounds, it can be seen that S. holocarpa wood contains many healthy and beneficial chemical components. The beneficial compounds in the extract could be useful in a wide range of industrial applications, such as biomedical, cosmetic, and food products. This study could provide scientific foundation for the research and development of S. holocarpa wood.

LC-QTOF-MS Analysis
Compounds were detected in the ethanol/methanol powder from the LC-QTOF-MS analysis (Table S4). Among all detected compounds, four main compounds-celastrol, rhododendrin, isocryptotanshinone, and arbutin showed a significant role in pharmaceutical and medicinal applications (Table 3). Compounds were detected in the ethanol/methanol powder from the LC-QTOFanalysis (Table S4). Among all detected compounds, four main compounds-celastrol, dodendrin, isocryptotanshinone, and arbutin showed a significant role in pharmaceu and medicinal applications (Table 3). Isocryptotanshinone is a natural bioactive product with anti-cancer effects [70]， an effective STAT3 inhibitor induction lung cancer cell apoptosis and promotion of tophagy [62]. One of the active chemical composition is celastrol, which is also know South Snake. This is a natural product with a variety of biological activities; it has a str antioxidant effect and can treat obesity [63]. It can also inhibit the growth of gastric ca cells and induce autophagy and apoptosis [64]. Furthermore, a synergistic effect on mitic acid-induced cardiomyocyte apoptosis has been described [65]. Rhododendrin i active anti-inflammatory compound activity. It is an ideal drug for the treatment o flammatory skin diseases such as psoriasis [66]. Rhododendron synthetic derivatives h potent tyrosinase inhibitory activity [67]. Arbutin is an ideal whitening agent for whi ing cosmetics. In cosmetics, it can effectively whiten and remove skin as well as gradu fade and remove skin freckles, chloasma, melanin, acne, and age spots. It is also hig safe and has no side effects such as irritation or sensitization. It has good compatib with various components of cosmetics. Furthermore, it is stable under ultraviolet irra tion [68,69]. Compared to GC-MS, LC-QTOF-MS is a more in-depth data test. It det more small organic molecules and makes the detected data more accurate.

Analysis of TGA
TG and DTG curves at different optimization temperature settings for all four ty of nanocatalyst treatments were obtained and are displayed in Figure 3. All four nano alyst treatments were about the same at different temperatures and at different ra However, with an increasing heating rate, the temperature range of the pyrolysis reac also increased. The starting and termination temperatures of each stage of the pyrol process moved slightly toward high temperatures. Therefore, the pyrolysis process four stages. Stage I was from the initial temperature to about 120 °C, which is the wa evaporation stage. In this stage, water evaporation resulted in mass loss [71]. The tem ature range of stage II was 120 to 265 °C, which was the transition stage of preheating. loss of mass at stage II was relatively slow, which showed that the pyrolysis rate steady. The mass loss mainly owed to the depolymerization and recombination of a sm Compounds were detected in the ethanol/methanol powder from the LC-QTOFanalysis (Table S4). Among all detected compounds, four main compounds-celastrol, r dodendrin, isocryptotanshinone, and arbutin showed a significant role in pharmaceut and medicinal applications (Table 3). Isocryptotanshinone is a natural bioactive product with anti-cancer effects [70]， an effective STAT3 inhibitor induction lung cancer cell apoptosis and promotion of tophagy [62]. One of the active chemical composition is celastrol, which is also know South Snake. This is a natural product with a variety of biological activities; it has a str antioxidant effect and can treat obesity [63]. It can also inhibit the growth of gastric can cells and induce autophagy and apoptosis [64]. Furthermore, a synergistic effect on mitic acid-induced cardiomyocyte apoptosis has been described [65]. Rhododendrin i active anti-inflammatory compound activity. It is an ideal drug for the treatment of flammatory skin diseases such as psoriasis [66]. Rhododendron synthetic derivatives h potent tyrosinase inhibitory activity [67]. Arbutin is an ideal whitening agent for whi ing cosmetics. In cosmetics, it can effectively whiten and remove skin as well as gradu fade and remove skin freckles, chloasma, melanin, acne, and age spots. It is also hig safe and has no side effects such as irritation or sensitization. It has good compatib with various components of cosmetics. Furthermore, it is stable under ultraviolet irra tion [68,69]. Compared to GC-MS, LC-QTOF-MS is a more in-depth data test. It det more small organic molecules and makes the detected data more accurate.

Analysis of TGA
TG and DTG curves at different optimization temperature settings for all four ty of nanocatalyst treatments were obtained and are displayed in Figure 3. All four nano alyst treatments were about the same at different temperatures and at different ra However, with an increasing heating rate, the temperature range of the pyrolysis reac also increased. The starting and termination temperatures of each stage of the pyrol process moved slightly toward high temperatures. Therefore, the pyrolysis process four stages. Stage I was from the initial temperature to about 120 °C, which is the wa evaporation stage. In this stage, water evaporation resulted in mass loss [71]. The tem ature range of stage II was 120 to 265 °C, which was the transition stage of preheating. loss of mass at stage II was relatively slow, which showed that the pyrolysis rate steady. The mass loss mainly owed to the depolymerization and recombination of a sm

LC-QTOF-MS Analysis
Compounds were detected in the ethanol/methanol powder from the LC-QTOFanalysis (Table S4). Among all detected compounds, four main compounds-celastrol, dodendrin, isocryptotanshinone, and arbutin showed a significant role in pharmaceu and medicinal applications (Table 3). Isocryptotanshinone is a natural bioactive product with anti-cancer effects [70]， an effective STAT3 inhibitor induction lung cancer cell apoptosis and promotion of tophagy [62]. One of the active chemical composition is celastrol, which is also know South Snake. This is a natural product with a variety of biological activities; it has a str antioxidant effect and can treat obesity [63]. It can also inhibit the growth of gastric ca cells and induce autophagy and apoptosis [64]. Furthermore, a synergistic effect on mitic acid-induced cardiomyocyte apoptosis has been described [65]. Rhododendrin i active anti-inflammatory compound activity. It is an ideal drug for the treatment o flammatory skin diseases such as psoriasis [66]. Rhododendron synthetic derivatives h potent tyrosinase inhibitory activity [67]. Arbutin is an ideal whitening agent for whi ing cosmetics. In cosmetics, it can effectively whiten and remove skin as well as gradu fade and remove skin freckles, chloasma, melanin, acne, and age spots. It is also hig safe and has no side effects such as irritation or sensitization. It has good compatib with various components of cosmetics. Furthermore, it is stable under ultraviolet irra tion [68,69]. Compared to GC-MS, LC-QTOF-MS is a more in-depth data test. It det more small organic molecules and makes the detected data more accurate.

Analysis of TGA
TG and DTG curves at different optimization temperature settings for all four ty of nanocatalyst treatments were obtained and are displayed in Figure 3. All four nano alyst treatments were about the same at different temperatures and at different ra However, with an increasing heating rate, the temperature range of the pyrolysis reac also increased. The starting and termination temperatures of each stage of the pyrol process moved slightly toward high temperatures. Therefore, the pyrolysis process four stages. Stage I was from the initial temperature to about 120 °C, which is the wa evaporation stage. In this stage, water evaporation resulted in mass loss [71]. The tem ature range of stage II was 120 to 265 °C, which was the transition stage of preheating. loss of mass at stage II was relatively slow, which showed that the pyrolysis rate steady. The mass loss mainly owed to the depolymerization and recombination of a sm

LC-QTOF-MS Analysis
Compounds were detected in the ethanol/methanol powder from the LC-QTOFanalysis (Table S4). Among all detected compounds, four main compounds-celastrol, dodendrin, isocryptotanshinone, and arbutin showed a significant role in pharmaceu and medicinal applications (Table 3). Isocryptotanshinone is a natural bioactive product with anti-cancer effects [70]， an effective STAT3 inhibitor induction lung cancer cell apoptosis and promotion of tophagy [62]. One of the active chemical composition is celastrol, which is also know South Snake. This is a natural product with a variety of biological activities; it has a str antioxidant effect and can treat obesity [63]. It can also inhibit the growth of gastric can cells and induce autophagy and apoptosis [64]. Furthermore, a synergistic effect on mitic acid-induced cardiomyocyte apoptosis has been described [65]. Rhododendrin i active anti-inflammatory compound activity. It is an ideal drug for the treatment o flammatory skin diseases such as psoriasis [66]. Rhododendron synthetic derivatives h potent tyrosinase inhibitory activity [67]. Arbutin is an ideal whitening agent for whi ing cosmetics. In cosmetics, it can effectively whiten and remove skin as well as gradu fade and remove skin freckles, chloasma, melanin, acne, and age spots. It is also hig safe and has no side effects such as irritation or sensitization. It has good compatib with various components of cosmetics. Furthermore, it is stable under ultraviolet irra tion [68,69]. Compared to GC-MS, LC-QTOF-MS is a more in-depth data test. It det more small organic molecules and makes the detected data more accurate.

Analysis of TGA
TG and DTG curves at different optimization temperature settings for all four ty of nanocatalyst treatments were obtained and are displayed in Figure 3. All four nano alyst treatments were about the same at different temperatures and at different ra However, with an increasing heating rate, the temperature range of the pyrolysis reac also increased. The starting and termination temperatures of each stage of the pyrol process moved slightly toward high temperatures. Therefore, the pyrolysis process four stages. Stage I was from the initial temperature to about 120 °C, which is the wa evaporation stage. In this stage, water evaporation resulted in mass loss [71]. The tem ature range of stage II was 120 to 265 °C, which was the transition stage of preheating. loss of mass at stage II was relatively slow, which showed that the pyrolysis rate steady. The mass loss mainly owed to the depolymerization and recombination of a sm  [68,69] Isocryptotanshinone is a natural bioactive product with anti-cancer effects [70], it's an effective STAT3 inhibitor induction lung cancer cell apoptosis and promotion of autophagy [62]. One of the active chemical composition is celastrol, which is also known as South Snake. This is a natural product with a variety of biological activities; it has a strong antioxidant effect and can treat obesity [63]. It can also inhibit the growth of gastric cancer cells and induce autophagy and apoptosis [64]. Furthermore, a synergistic effect on palmitic acid-induced cardiomyocyte apoptosis has been described [65]. Rhododendrin is an active anti-inflammatory compound activity. It is an ideal drug for the treatment of inflammatory skin diseases such as psoriasis [66]. Rhododendron synthetic derivatives have potent tyrosinase inhibitory activity [67]. Arbutin is an ideal whitening agent for whitening cosmetics. In cosmetics, it can effectively whiten and remove skin as well as gradually fade and remove skin freckles, chloasma, melanin, acne, and age spots. It is also highly safe and has no side effects such as irritation or sensitization. It has good compatibility with various components of cosmetics. Furthermore, it is stable under ultraviolet irradiation [68,69]. Compared to GC-MS, LC-QTOF-MS is a more in-depth data test. It detects more small organic molecules and makes the detected data more accurate.

Analysis of TGA
TG and DTG curves at different optimization temperature settings for all four types of nanocatalyst treatments were obtained and are displayed in Figure 3. All four nanocatalyst treatments were about the same at different temperatures and at different rates. However, with an increasing heating rate, the temperature range of the pyrolysis reaction also increased. The starting and termination temperatures of each stage of the pyrolysis process moved slightly toward high temperatures. Therefore, the pyrolysis process had four stages. Stage I was from the initial temperature to about 120 • C, which is the water-evaporation stage. In this stage, water evaporation resulted in mass loss [71]. The temperature range of stage II was 120 to 265 • C, which was the transition stage of preheating. The loss of mass at stage II was relatively slow, which showed that the pyrolysis rate was steady. The mass loss mainly owed to the depolymerization and recombination of a small amount of high-content polymer in the sample [72]. Stage III was the volatilization analysis stage and the main stage of mass loss. The mass loss range of the four samples is 265-390 • C (Figure 3a,b), 265-360 • C (Figure 3c) and 265-380 • C (Figure 3d), respectively. The temperature increased Polymers 2022, 14, 4385 9 of 17 in S. holocarpa wood samples in this temperature range. The cellulose and hemicellulose were rapidly cracked to form a large amount of volatile gas, which caused mass loss and caused the TGA curve to drop sharply [73]. At this stage, the volatile analysis yielded 80% to 90% of the mass loss for the entire temperature range. The peak of pyrolysis of cellulose appearing at 330 • C was at first due to high polymerization that formed oligosaccharides, which in turn decomposed and formed small molecules of gas and condensable volatiles of macromolecules. The pyrolysis temperature of hemicellulose was generally close to 200 • C, and the pyrolysis peak occurs between 265 • C-390 • C after pyrolysis [74]. amount of high-content polymer in the sample [72]. Stage III was the volatilization analysis stage and the main stage of mass loss. The mass loss range of the four samples is 265-390 °C (Figure 3a and b), 265-360 °C (Figure 3c) and 265-380 °C (Figure 3d),.respectively. The temperature increased in S. holocarpa wood samples in this temperature range. The cellulose and hemicellulose were rapidly cracked to form a large amount of volatile gas, which caused mass loss and caused the TGA curve to drop sharply [73]. At this stage, the volatile analysis yielded 80% to 90% of the mass loss for the entire temperature range. The peak of pyrolysis of cellulose appearing at 330 °C was at first due to high polymerization that formed oligosaccharides, which in turn decomposed and formed small molecules of gas and condensable volatiles of macromolecules. The pyrolysis temperature of hemicellulose was generally close to 200 °C, and the pyrolysis peak occurs between 265 °C-390 °C after pyrolysis [74]. The stage IV was the carbonization stage. When the temperature exceed 400 °C, the residue gradually decomposes into carbon or ash, and the mass loss is minimal.. This stage was mainly the pyrolysis of lignin in comparison with the pyrolysis of cellulose and hemicellulose. In the process, the temperature range of the lignin pyrolysis was wide, generally occurring at 200-500 °C, and lignin pyrolysis generated more coke. The aromatic ring structure in the initial thermal cracking product decomposed and condensed after 500 °C to form a small molecular substance [75]. The sample decomposition temperatures in Figure 3 are 230, 255, 240 and 245 °C, respectively, which indicates that the thermal performance of the samples was almost unchanged.
The results showed that the DTGmax values for 750 °C, 850 °C, 950 °C (20 °C/min), and 950 °C (100 °C/min) were 373, 371, 372, and 360 °C, respectively (Figure 3). The DTG curve showed that when the temperature was about 115°C (Figure 3a and b) and 105°C( Figure  3c and d), the mass loss rate of S. holocarpa wood sample was one peak. This is because the cellulose, hemicellulose, and lignin composition of S. holocarpa wood samples treated with different nanocatalysts changed. Between 265 and 400 °C, mainly the cleavage of some sugars and phenols can be observed. The four samples increased gradually at the DTGmax value in the pyrolysis rates. This showed that the use of nanocatalysts could The stage IV was the carbonization stage. When the temperature exceed 400 • C, the residue gradually decomposes into carbon or ash, and the mass loss is minimal. This stage was mainly the pyrolysis of lignin in comparison with the pyrolysis of cellulose and hemicellulose. In the process, the temperature range of the lignin pyrolysis was wide, generally occurring at 200-500 • C, and lignin pyrolysis generated more coke. The aromatic ring structure in the initial thermal cracking product decomposed and condensed after 500 • C to form a small molecular substance [75]. The sample decomposition temperatures in Figure 3 are 230, 255, 240 and 245 • C, respectively, which indicates that the thermal performance of the samples was almost unchanged.
The results showed that the DTG max values for 750 • C, 850 • C, 950 • C (20 • C/min), and 950 • C (100 • C/min) were 373, 371, 372, and 360 • C, respectively ( Figure 3). The DTG curve showed that when the temperature was about 115 • C (Figure 3a,b) and 105 • C (Figure 3c,d), the mass loss rate of S. holocarpa wood sample was one peak. This is because the cellulose, hemicellulose, and lignin composition of S. holocarpa wood samples treated with different nanocatalysts changed. Between 265 and 400 • C, mainly the cleavage of some sugars and phenols can be observed. The four samples increased gradually at the DTGmax value in the pyrolysis rates. This showed that the use of nanocatalysts could promote the catalytic cracking of sugars and phenols and that nano−Co 3 O 4 had the best catalytic effect [76].

TG−FTIR Analysis
Three-dimensional TG−FTIR spectra of all four nanocatalyst treatments are shown in Figure 4. The process of TG−FTIR analysis can be split into four stages. During stage I, the pyrolysis temperatures of S. holocarpa wood, S. holocarpa wood/NiO, S. holocarpa wood/Co 3 O 4 , and S. holocarpa wood/NiO+Co 3 O 4 were 74, 79, 68, and 66 • C, respectively. A slight shoulder was shown in the wave number of 4000-3400 cm −1 , indicating that the pyrolysis process of S. holocarpa wood corresponded. The volatilization of free water and the weight loss of the sample at this stage were small. During stage II, at 74-220 • C, 79-225 • C, 68-215 • C, and 66-218 • C, the overall curve was even, which proved that the pyrolysis rate was steady [77]. One type consisted of small-molecule gases such as CO 2 , CO, CH, and H 2 O. The other type consisted of typical tar components such as phenol, aldehyde, and acid [78].
Polymers 2022, 14, x FOR PEER REVIEW 11 of 17 promote the catalytic cracking of sugars and phenols and that nano−Co3O4 had the best catalytic effect [76].

TG−FTIR Analysis
Three-dimensional TG−FTIR spectra of all four nanocatalyst treatments are shown in Figure 4. The process of TG−FTIR analysis can be split into four stages. During stage I, the pyrolysis temperatures of S. holocarpa wood, S. holocarpa wood/NiO, S. holocarpa wood/Co3O4, and S. holocarpa wood/NiO+Co3O4 were 74, 79, 68, and 66 °C, respectively. A slight shoulder was shown in the wave number of 4000-3400 cm −1 , indicating that the pyrolysis process of S. holocarpa wood corresponded. The volatilization of free water and the weight loss of the sample at this stage were small. During stage II, at 74-220 °C, 79-225 °C, 68-215 °C, and 66-218 °C, the overall curve was even, which proved that the pyrolysis rate was steady [77]. One type consisted of small-molecule gases such as CO2, CO, CH, and H2O. The other type consisted of typical tar components such as phenol, aldehyde, and acid [78]. During stage III, the precipitation content of several light gases increased significantly, cellulose and hemicellulose decomposed rapidly and produced a lot of volatile gases, S. holocarpa wood had the most severe pyrolysis reaction, and weight-loss rate was highest at 390 °C. The fourth stage was the carbonization stage after 400 °C; the weight loss was extremely low and the residue slowly decomposed into carbon and ash. Above 500 °C, the aromatic ring structure in the initial thermal cracking product decomposed and condensed to form a small molecular substance. At this stage, CO was the main precipitated gas, and further, a small amount of CO2 was precipitated; no other products were precipitated [79]. At the same time, other substances were precipitated during the pyrolysis process, and absorption peaks appeared in the infrared spectrum in the range of 2500- During stage III, the precipitation content of several light gases increased significantly, cellulose and hemicellulose decomposed rapidly and produced a lot of volatile gases, S. holocarpa wood had the most severe pyrolysis reaction, and weight-loss rate was highest at 390 • C. The fourth stage was the carbonization stage after 400 • C; the weight loss was extremely low and the residue slowly decomposed into carbon and ash. Above 500 • C, the aromatic ring structure in the initial thermal cracking product decomposed and condensed to form a small molecular substance. At this stage, CO was the main precipitated gas, and further, a small amount of CO 2 was precipitated; no other products were precipitated [79]. At the same time, other substances were precipitated during the pyrolysis process, and absorption peaks appeared in the infrared spectrum in the range of 2500-2250 and 1500-1250 cm −1 (Figure 4). This suggested that the precipitation of macromolecules such as aldehydes, hydrocarbons, carboxylic acids, and alcohols is due to C-O stretching vibration and C-C skeleton vibration in S. holocarpa wood [80]. By FTIR, many compounds were determined, and their characteristic absorbances at 4000-3400, 3050-2650, 2400-2240, and 2230-2000 cm −1 were identified, representing CH 4 , CO 2 , H 2 O, and CO [81]. The C=O tensile absorbance was between 1880 cm −1 and 1620 cm −1 , which represents aldehydes, ketones, and acidic organic components. Between 1600 cm −1 and 400 cm −1 , the spectral intensity of pyrolysis volatiles was the strongest, due to the characteristic absorption rate of some organic compounds [82].
The results show that the spectrum (a) reaction of S. holocarpa wood was relatively gentle and the spectrum (b-d) reaction with nanocatalysts was more intense, especially the spectrum (c) reaction (Figure 4). This showed that metal oxide catalysis was beneficial to the pyrolysis of S. holocarpa wood and that nano−Co 3 O 4 had a better catalytic effect. The approximate maximum weight-loss temperature was at 340-390 • C, releasing a large number of complex organic volatiles, including carbonyl and oxy groups, which represented carboxyl, ketone, aldehyde, and alcohol. These are the main components of bio-oil. They can also synthesize a variety of drugs, pesticides, and their intermediates, and have a wide range of industrial application prospects. The results of TG−FTIR showed that S. holocarpa wood could be used to produce extracted bio-oil by pyrolysis. In addition, the size of metal nanoparticles had a great influence on catalytic function. Future TG−FTIR studies can start by changing the types of catalysts and reducing the particle sizes of the catalysts. In comparison of all the samples, the highest content of S. holocarpa wood/Co3O4 was 51.12% (acid ester, ether alcohol and aldehyde ketone). The results showed that nano−Co3O4 was the best catalyst for the reaction, which can improve the biomass composition and maximize the biomass output. As nano−Co3O4 is a catalyst with high catalytic activity, the pyrolysis rate and efficiency could be greatly improved [83,84]. In other re- In comparison of all the samples, the highest content of S. holocarpa wood/Co 3 O 4 was 51.12% (acid ester, ether alcohol and aldehyde ketone). The results showed that nano−Co 3 O 4 was the best catalyst for the reaction, which can improve the biomass composition and maximize the biomass output. As nano−Co 3 O 4 is a catalyst with high catalytic activity, the pyrolysis rate and efficiency could be greatly improved [83,84]. In other reports, nano−Co 3 O 4 could effectively improve redox reactions [85,86]. In addition, the shape of a Co 3 O 4 nanocatalyst was more important than its size dependence [87,88]. The Py/GC−MS results showed that nano−NiO is not as effective as nano−Co 3 O 4 . However, nickel oxide nanocatalysts studied by Dawood et al. could effectively catalyze the conversion of Brachychiton populneus seed oil into biodiesel with high catalytic efficiency [89]. This may be greatly related to the concentration and shape of the catalysts used [90]. The nanocatalysts were introduced into the biomass pyrolysis process to realize the catalytic reaction of pyrolysis gas. Compared with pyrolysis, catalytic cracking could achieve directional catalytic conversion, promote reaction balance, and obtain more target products [91]. The use of low-cost and high-efficiency nanocatalysts is of great significance to the development of renewable energy [92]. The results of this study are conducive to the use of S. holocarpa wood as a biomass energy material and provide a scientific basis for the development and utilization of S. holocarpa wood.

Conclusions
In this study, S. holocarpa wood was used as the research object to prepare bio-oil. S. holocarpa wood had been proven to have healthy and beneficial chemical components and be useful in biomedicine, food additives, and industrial applications. This study also provided fundamental insight on the role of nanocatalysts in the pyrolysis process, in which multiple volatile compounds were detected during the reaction: important components of extracted bio-oil (including ketones, acids, and alcohols). The results showed that the nanocatalysts affected the composition of pyrolysis products in Py/GC−MS analysis. The wood samples containing nano-Co 3 O 4 tended to have good catalytic activity, which could efficaciously promote the catalytic cracking of S. holocarpa wood. This study, exploring the relationship between wood biomass, pyrolysis, and nanocatalysts, is conducive to the development and utilization of S. holocarpa wood, in addition to advocating for contribution and scientific knowledges in green science and green synthesis application. This is the first study that incorporated nanocatalysts in S. holocarpa wood. The nanocatalysts showed great potential for the production of value-added products in the pyrolysis results of S. holocarpa wood. However, the possibility of high production remains to be confirmed. The combination of nanocatalysts and pyrolysis is an innovative method to improve pyrolysis products. In the future, the catalytic effect of pyrolysis could be improved by optimizing the morphology, concentration, type, and various pyrolysis setting parameters of nanocatalysts, so as to maximize the catalytic effect of pyrolysis.