Formation Of Phenol Research Articles

Novel detection of primary and secondary volatiles from cedar pyrolysis using in-situ pyrolysis double ionization time-of-flight mass spectrometry

Exploration of primary and secondary volatiles from biomass pyrolysis is of great importance for revealing biomass pyrolysis mechanisms. In this study, a novel in-situ pyrolysis time-of-flight mass spectrometry with double ionization sources was taken to in-situ detect primary volatiles and secondary volatiles from volatiles-volatiles interactions during cedar pyrolysis. Herein, height-varied quartz sand was applied to regulate volatiles-volatiles interactions, and the interaction mechanisms were examined with assistance with EPR analysis. The results show that primary volatiles mainly contain aliphatic chains, phenols, furans, G-type guaiacols and polycyclics. G-type guaiacols interactions were intensified by increasing the quartz sand height, and promoted for the formation of phenols, polycyclics and aromatic radical- and catechol radical-contained coke. During secondary reactions, the furans tend to undergo deacetylation and volatiles-volatiles condensation to form 2-furanmethanol and σ type radical-contained coke. This study provided a novel method to understand the release and secondary evolution behaviors of primary volatiles during biomass pyrolysis.

In-depth understanding on the early stage of phenolic resin thermal pyrolysis through ReaxFF-molecular dynamics simulation

• The early pyrolysis of PR is clarified from the view of cleavage reaction. • The cleavage reaction of PR occurs beside (CR b ) and on (CR o ) the backbone. • The H• from CR b is the initial species, leading to the formation of H 2 and H 2 O. • The decreasing char yield is caused by the loss of the terminal phenol from CR o . Acquiring deep understanding of the pyrolysis process of phenolic resin (PR) and its mechanism is of pivotal importance to develop new applications. Herein, novolac resin (NR) is used as the structural model to investigate the pyrolysis mechanism by carrying out a series of reactive force field molecular dynamics simulations. The structural evolution of NR and the formation process of small molecular species at nine different kinds of NR analogous models are investigated. The results show that the early pyrolysis process of NR involves mainly two aspects: the cleavage reactions beside backbone (CR b ) and on backbone (CR o ). The hydrogen radical produced from the cleavage of the methylene C—H bond, which belong to the CR b process, is the initial species detected during the pyrolysis process, and leads to the formation of H 2 O and H 2 . Besides, the C—C bond cleavage of the methylene bridge is predominant in the CR o process, which takes place with almost equal probability. It mainly results in the formation of phenols, diphenols, polyphenols, and cross-linked structures. The volatilization of the phenol compounds stripped from the terminal groups is a critical process to reduce the char yield of the PR. Moreover, the main small-molecule species detected during the early pyrolysis of NR are H 2 O, H 2, and CO, and the higher energy is necessary to generate CO than H 2 O and H 2 . This work deepens the understanding of the PR pyrolysis mechanism and provides valuable insights to develop its applications.

Ultrasound-based synthesis, SC-XRD, NMR, DFT, HSA of new Schiff bases derived from 2-aminopyridine: Experimental and theoretical studies

The present work is related to the rapid and efficient preparation of Schiff bases (1 and 2) by reaction of 2-aminopyridine derivatives with 3-ethoxysalicylaldehyde under ultrasonic irradiation. The advantages, of using ultrasonic irradiation, are short reaction time, high yield and the ability to carry out large scale reactions. After characterization by NMR spectroscopic technique and elemental analyses, the crystal structures of compounds were confirmed by single crystal X-ray analysis (SC-XRD). For further elaboration of non-covalent interactions in the stabilization of packing of molecules, Hirshfeld surface (HS) inspection was accomplished by using crystal explorer software. B3LYP/Def2-TZVP level of theory was used to calculate electronic and structural parameters of synthesized compounds. Optimized structures and calculated data showed good correlation with experimental ones. In addition, two models of keto and phenol tautomerism were studied by calculating thermodynamic parameters and molecular electrostatic potential. Results showed that there are both nucleophilic and electrophilic centers in keto form, while only nucleophilic center is present in phenol form.

Kinetics of Alkali-Catalyzed Monomethylol Phenol Formation for F/P < 1 by 1H NMR Spectroscopy for Ablative Applications

The formation of monomethylol phenols and their ratio during the polymerization reaction of phenol (P) and formaldehyde (F) dictate the final product and thereby formulated composite properties. Here, we have studied the kinetics of ortho- and para-methylol phenol formation during the polymerization (F/P = 0.89) under alkaline conditions (pH 7.3–7.8) at 60, 70, 80 and 90 °C using 1H NMR spectroscopy. 13C NMR validated the results obtained. On increasing reaction temperature, reactant consumption rate and ratio of ortho- to para-methylol phenol (o/p) formation increased. The o/p also increased with an increase in reaction time for all the temperatures studied. The reaction follows pseudo-first-order kinetics with respect to formaldehyde. The activation energies of the addition reaction between phenol and formaldehyde and the formed prepolymers are determined. Thus, 1H NMR appears handy in studying the kinetics of prepolymers formed.

Phycoremediation of phenol-polluted petro-industrial effluents and its techno-economic values as a win-win process for a green environment, sustainable energy and bioproducts.

The discharge of the toxic phenol-polluted petro-industrial effluents (PPPIE) has severe environmental negative impacts, thus it is mandatory to be treated before its discharge. The objective of this review was to discuss the sustainable application of microalgae in phenols degradation, with a special emphasis on the enzymes involved in this bioprocess and the factors affecting the success of PPPIE phycoremediation. Moreover, it confers the microalgae bioenergetic strategies to degrade different forms of phenols in PPPIE. It also points out the advantages of the latest application of bacteria, fungi and microalgae as microbial consortia in phenols biodegradation. Briefly, phycoremediation of PPPIE consumes carbon dioxide emitted from petro-industries for; valorization of the polluted water to be reused and production of algal biomass which can act as a source of energy for such integrated bioprocess. Besides, the harvested algal biomass can feasibly produce; third-generation biofuels, biorefineries, bioplastics, fish and animal feed, food supplements, natural dyes, antioxidants and many other valuable products. Consequently, this review precisely confirms that the phycoremediation of PPPIE is a win-win process for a green environment and a sustainable future. Thus, to achieve the three pillars of sustainability; social, environmental and economic; it is recommendable to integrate PPPIE treatment with algal cultivation. This integrated process would overcome the problem of greenhouse gas emissions, global warming and climate change, solve the problem of water-scarce, and protect the environment from the harmful negative impacts of PPPIE.

Graphene vanadic acid (GVA) as a novel heterogeneous catalyst for highly selective benzene hydroxylation under mild conditions

In the present study, Graphene Vanadic Acid (GVA) is introduced as a novel catalyst for high-efficiency hydroxylation of benzene to phenol using hydrogen peroxide at ambient conditions. Graphene oxide as a famous carbon support has converted to a high-performance catalyst through the functionalization using vanadium oxytrichloride (VOCl3). This new carbon compound is regarded as the efficient catalyst due to the prominent advantages such as high-recativity and reusability, facile preparation, active Lewis and Bronsted acid sites, high potential for development of various oxidation reactions, and high thermal, chemical, and physical stability due to the regular carbon structure. GVA progressed the benzene oxidation toward the phenol formation as a useful raw material. Cause of the considerable reactivity of the synthesized catalyst, a minimum amount of hydrogen peroxide was required and the benzene oxidation carried out using an equimolar ratio of benzene/H2O2, and phenol obtained with a remarkable yield (28.2%) as the sole product.

Upcycling of waste teabags via catalytic pyrolysis in carbon dioxide over HZSM-11

Disruptive impact of everyday waste on the environment makes it a serious growing concern. Even though disposal and reclaim strategies are firstly considered to overcome this problem, upcycling of the waste via thermochemical transformations (e.g., pyrolysis) will eventually be essential to reconvert massive quantities of waste materials. Here, to seek a method to valorize everyday waste, the effects of CO2 and HZSM-11 catalyst on pyrolytic products produced via pyrolysis of waste teabag were investigated. For non-catalytic pyrolysis of waste teabag, CO2 increased the yield of pyrolytic gases and suppressed the formation of benzenes, phenolics, and polycyclic aromatic hydrocarbons, compared to N2. For catalytic pyrolysis of waste teabag over HZSM-11 more CO2 was transformed to CO than non-catalytic pyrolysis. The extent of CO2 conversion into CO was greater in CO2 environment than in N2 environment. A synergistical use of CO2 and HZSM-11 in pyrolysis of waste teabag enhanced the production of caprolactam (6.8 wt% yield), a value-added nylon monomer. The char derived from waste teabag via the pyrolysis in CO2 over HZSM-11 had higher heating value of 26 MJ kg−1 comparable to HHV of coal. The synergistical employment of HZSM-11 catalyst and CO2 pyrolysis medium has a significant feature of upcycling everyday waste such as waste teabag.

The pyrolysis of lignin: Pathway and interaction studies

Three different lignin samples (alkali lignin, THF separated lignin) and hemicellulose removed biomass samples were pyrolyzed at various temperatures and heating rate in a wire mesh reactor (WMR). The product distribution and characterisation of liquid product were analyzed and compared to obtain the pyrolysis behavior of lignin and the possible interaction. Different reactivities were observed for the studied components. The pathway of lignin pyrolysis was proposed. Heating rate and temperature played a significant role on the lignin and biomass pyrolysis. At intermediate temperatures of 450–525 °C, the phenols in liquid products were at maximum, while lower and higher temperatures promoted to the formation of dimer compounds in liquid product·THF soluble lignin favored the production of liquid, while THF insoluble lignin mainly formed solid residues. The interaction between THF separated lignin can promote the formation of phenols through the cracking of carboxylic acid, ketone and aldehyde and inhibit the coupling reaction of free radicals into dimer compounds. An interaction between lignin and cellulose was also observed leading to a lower solid residue but a higher yield of liquid. The interaction between lignin and cellulose also promoted the secondary decomposition of guaiacol derivates forming new compounds such as benzene, phenol and p-xylene and inhibited the condensation reaction of lignin.

Complexes of carboxylato pillar[6]arene with Brooker-type merocyanines: Spectral properties, pKa shifts and the design of a displacement assay for trimethyl lysine

The supramolecular complexes of three strongly solvatochromic dyes, Brooker’s merocyanine (M1) and its two derivatives (M2, M3) with carboxylato pillar[6]arene (WP6) were studied in aqueous solutions. The dye-WP6 mixtures were described in terms of four equilibrium reactions: the acidic dissociations of the pyridinium phenols into the zwitterionic phenolates, the acidic dissociations of the complexed phenols, the bindings of the phenol form dyes to WP6 and the bindings of the phenolates to WP6. The equilibrium constants were determined by an analysis of the absorption spectra. It was found that the acidity of the phenol form merocyanines were largely reduced on complexation, pKa shifts of 1.1–1.6 units were observed. In neutral solutions, the complexes of the phenol forms of M1 and M2 were dominant, in contrast to the more acidic M3 (a dibromo derivative), of which the phenolate complex was more stable. Comparing the spectral properties, the binding constants and the pKa-s of the dye-WP6 complexes, the complex M3⋅WP6 was chosen to be tested as a displacement assay. It was demonstrated that this complex functioned as a colorimetric indicator displacement assay which discriminated trimethyl lysine from other lysine derivatives.

Nutrition of local wild edible fern (Diplazium esculentum) leaves

Vegetable fern species distributed throughout the world are diverse, but there is a lack of scientific data about the nutritional content of local vegetable ferns. This study aimed to provide preliminary data of Diplazium esculentum nutrition obtained from Bone Bolango District, Gorontalo area, Indonesia, in order to support the developing of pharmaceutical and mixed animal feed products. Tests for the proximate characteristics of leaf extracts and the phytochemical analysis were carried out through qualitative screening following Indonesian National Standard (SNI) Method year 2006, while the detail amino acid compound analyzed using Gas Chromatography Mass Spectrometry (GCMS) method. The results showed that D. esculentum from Gorontalo Land is rich with proteins and amino acids. The amount of protein and fat is detected as 21.52 ± 2.70% and 2.47 ± 0.97% respectively. The fern also contains complete secondary metabolites in the form of alkaloids, saponins, tannins, phenolics, flavonoids, triterpenoids, steroids, and glycosides with a high amount.

Potential of ciplukan extract (Physalis angulata L.) and patchouli waste (pogostemon patchouli pellet) as alternative sources of phytogenic feed additive

This study aims to examine the potential of ciplukan and patchouli oil refining waste as alternative sources of phytogenic feed additive to replace the Antibiotic Growth Promotor (AGP) in livestock. The research was carried out by using the method of extraction and identification of phytogenic components of ciplukan and patchouli waste as well as in vitro for antibacterial and antioxidant tests of ciplukan leaf extract and patchouli waste. The variables observed were percentage yield, nutritional content, phytochemicals, phytogenic compounds, antibacterial inhibition and antioxidant content of ciplukan leaf extract and patchouli waste. Data analysis was carried out descriptively and tabulated according to the research variables. The results showed that the extraction using 96% ethanol solvent produced different yields, the highest yield was found in ciplukan, namely 9.75% and patchouli waste of 1.02% by weight of fresh ingredients. The nutritional content of ciplukan and patchouli waste respectively contains crude protein 27.79 and 14.19%, crude fiber 7.08 and 17.09%, fat 3.43 and 3.85%, BETN 27.46 and 40.87%, and the antioxidant content tends to be higher in ciplukan, namely 75.70% and 73.53% patchouli waste. Based on the results of the phytochemical test, patchouli waste extract contains bioactive substances in the form of alkaloids, flavonoids, phenols, tannins, saponins, steroids and terpenoids as well as essential oils, while the ciplukan extract does not contain terpenoids and essential oils. The results of the antibacterial test showed that patchouli waste extract had the largest inhibition zone against Escherichia coli and Salmonella bacteria compared to the ciplukan extract with an average diameter of 12.50 and 8.50 mm. Conclusion patchouli waste extract has the potential to be used as an alternative source of phytogenic feed additive because it contains phytogenic bioactive substances and can act as antibacterial.

Formation of p-Unsubstituted Phenols in Base-catalyzed Lignin Depolymerization

Lignin valorization is one of the biggest challenges for developing biomass-based chemical industry. Recent innovative works has enabled depolymerization of lignin to the monomers with the yield close to theoretical maximum. The main product is a mixture of phenols derived from the cleavage of β-O-4 linkages between phenylpropanoid units. However, the obtained highly functionalized phenols are not common in current industry and, therefore, needs further processing for the utilization in intended applications. The present study shows that simple phenols without functional groups at para-position form selectively in base-catalyzed depolymerization of lignin. The yield is not sufficiently high, up to 6.9% on a carbon basis under the examined conditions, but the selectivity among released lignin monomers reaches 80%. The study also discusses the mechanism of p-unsubstituted phenols formation.

Insight into Tar Formation Mechanism during Catalytic Pyrolysis of Biomass over Waste Aluminum Dross

Tar is one of major products from biomass pyrolysis. Its formation mechanism in a catalytic pyrolysis system comprising pine sawdust and waste aluminum dross (AD) is investigated with the aid of analytical methods including thermogravimetric analysis (TG), Nuclear Magnetic Resonance (NMR), electron paramagnetic resonance (EPR), and gas chromatography coupling with mass spectrometry (GC-MS). The results show that AD plays a vital role in cleavage of C-O bonds to enhance selective formation of furans, ketones, and phenols. The catalytic pyrolysis is initiated by active C-O-M intermediate formation that accelerates C-O bond cleavage and generates great amounts of free radicals to 1020 spins/g at 300–500 °C. Compared with pure pine pyrolysis, the percentage of glucosidic bonds from cellulose decreases from 14.00% to 9.66% at 500 °C; the etherified guaiacyl is more actively ruptured and disappears at 700 °C. Furans and ketones increase from 17.45% to 22.23% and 6.71% to 10.80% at 500 °C, respectively. Phenols increase from 66.75% to 71.57%. The preferential production of higher value-added products via catalytic pyrolysis between biomass and industrial wastes may bring new insight to the simultaneous valorization of agricultural, municipal, and industrial waste.

Optimization of lignin conversion to phenol via partial oxidation of synthesized wastewater containing lignin

This work was to optimize operating parameters for phenol production via partial oxidation. The essential settings, NaOH loading of 4–20 g/L, reaction temperatures of 140–180 °C, and time of 15–45 min, were set as the independent parameters for designing the experiments. A set of tests was generated using Box–Behnken Design (BBD) and performed in a high-pressure reactor at the constant air pressure of 2 bars. A produced phenol concentration was assigned as a response target for evaluating an optimal condition. From the results, a quadratic model of actual data was fit with high accuracy (R2 of 94.1%). A response surface methodology (RSM) was used to evaluate the operating parameters effect on the phenol formation. It showed that the temperature rising affected phenol formation due to the creation of aldehydes at low temperatures and phenol re-polymerization. The presence of NaOH plays an essential role in the production of phenol. It may increase the hydroxyl group’s rate to an aromatic ring that yields a high percentage of phenol production. For the reaction time, the longer time gave a higher yield of phenol. However, it slightly increased after 30 min. The predicted optimal condition was determined at the temperature of 161 °C, the NaOH loading of 16.4 mg/L, and the reaction time of 36.2 min. Three experiments were performed at the optimal point to verify the prediction. It was found that the phenol concentration of 30 ± 1 mg/L was yielded at this condition. Moreover, the reaction temperature and the initial pressure of air were not severe. It indicates that the partial oxidation of aqueous lignin solution can produce phenol at mild conditions.

Insights into the Binding of Dietary Phenolic Compounds to Human Serum Albumin and Food-Drug Interactions.

The distribution of drugs and dietary phenolic compounds in the systemic circulation de-pends on, among other factors, unspecific/specific reversible binding to plasma proteins such as human serum albumin (HSA). Phenolic substances, present in plant-derived feeds, foods, beverages, herbal medicines, and dietary supplements, are of great interest due to their biological activity. Recently, considerable research has been directed at the formation of phenol–HSA complexes, focusing above all on structure–affinity relationships. The nucleophilicity and planarity of molecules can be altered by the number and position of hydroxyl groups on the aromatic ring and by hydrogenation. Binding affinities towards HSA may also differ between phenolic compounds in their native form and conjugates derived from phase II reactions. On the other hand, food–drug interactions may increase the concentration of free drugs in the blood, affecting their transport and/or disposition and in some cases provoking adverse or toxic effects. This is caused mainly by a decrease in drug binding affinities for HSA in the presence of flavonoids. Accordingly, to avoid the side effects arising from changes in plasma protein binding, the intake of flavonoid-rich food and beverages should be taken into consideration when treating certain pathologies.

Catalytic mechanisms of potassium salts on pyrolysis of β-O-4 type lignin model polymer based on DFT study

In this study, the possible catalytic mechanisms of potassium salts on lignin pyrolysis was investigated with two β-O-4 type lignin model dimers with different oxygen functional groups on Cα using density functional theory (DFT) calculations. It was found that potassium salts (such as KOH and K2CO3) can react with phenol hydroxyl in lignin to form organic-K and further catalyze pyrolysis progress. Through this catalytic mechanism, potassium salts promoted the removal of Cα on specific intermediates and the demethylation of methoxy groups during β-O-4 type lignin pyrolysis, promoted the decomposition of intermediates, and facilitated the formation of phenol and CO2.

Gas-phase hydrodeoxygenation (HDO) of guaiacol over Pt/Al2O3 catalyst promoted by Nb2O5

Pt/xNb2O5/(100-x)Al2O3 (x = 0, 5, 20, 100, wt.%) catalysts were tested on the gas phase hydrodeoxygenation (HDO) of guaiacol (2-methoxyphenol, C7H8O2), model compound representative of the lignin-derived portion of the bio-oil produced after pyrolysis or HTL. The physicochemical properties of the catalysts were analyzed by XRD, N2 physisorption, CO chemisorption, and temperature programmed desorption of isopropylamine. The catalytic performances were evaluated in a continuous flow system at atmospheric pressure with the aim of reducing the oxygen content of the guaiacol molecule as an upgrading step of the biomass processing. The influence of H2 partial pressure, temperature, space velocity, and pure supports performance on both activity and selectivity was determined. The Pt/Nb2O5 catalyst exhibited superior oxygen removal. Niobia addition enhanced the selectivity towards phenol while Pt/Al2O3 formed mainly catechol. The interaction between Pt and NbOx species probably enables oxophilic sites formation which enhances DDO reaction towards phenol formation and less deactivation even at low hydrogen content.

Targeted profiling reveals metabolic perturbations in cryptogein-cotransformed hairy root cultures of Nicotiana tabacum

Although β-cryptogein gene expression was known to induce growth and phenolic metabolites accumulation in tobacco, however, the consequence on specialized metabolites other than phenolic has been scantly studied, and no report on the changes in primary metabolites is available. Tobacco (Nicotiana tabacum) hairy root cultures expressing β-cryptogein under CaMV 35S promoter were described here. GC–MS and HPLC–DAD based analyses of volatile and non-volatile metabolites including phenolic were carried out to study the variations in the levels of metabolites (both primary and specialized) in transgenic lines as compared to controls. Wall-bound phenolics and three forms of soluble phenolics (free, glycosyl-bound and ester-bound soluble phenolics) as well as chlorogenic acid contents were compared between cryptogein-cotransformed and control lines. In support of metabolite changes, semiquantitative expression analyses of selected genes of phenylpropanoid and terpenoid pathways viz. phenylalanine ammonia lyase (PAL), 4-coumaryl CoA ligase (4CL), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and 1-deoxy-d-xylulose-5-phosphate synthase (DXS), were performed. Furthermore, activities of important enzymes (PAL and 4CL) involved in phenylpropanoid pathway were analyzed. Increase of phenolic compounds, fatty acid-derivatives, alkaloids (nicotine and nornicotine), benzenoids, sugars (sucrose, fructose, galactose and lactose) and a few metabolites originated from glycolysis pathway intermediates were noticed in Ri-crypt-transformed hairy roots (RCTHR) with decline in the contents of terpenoids and many amino acids (except proline). Increased gene expressions of PAL and 4CL along with enhanced activities of respective enzymes in RCTHR were supported the phenolics accumulation. Reduced expressions of HMGR and DXS genes were observed which supported the reduced amount of terpenoid metabolites. This study suggests a possible channelling of carbon pool towards phenylpropanoid/benzenoid pathway as well as lipoxygenase pathway and nicotine biosynthesis in tobacco hairy roots expressing a β-cryptogein gene.

Catalytic fast Co-Pyrolysis of sewage sludge−sawdust using mixed metal oxides modified with ZSM-5 catalysts on dual-catalysts for product upgrading

Catalytic fast co-pyrolysis of sewage sludge and sawdust was performed using Py/GC-MS for pyrolytic product upgrades. Metal oxides (NiO and MoO3) and ZSM-5 catalysts had been introduced into single catalytic pyrolysis. The combination of NiO + MoO3 in mixed metal oxides (MMOs) was modified with ZSM-5 under a dual-catalyst with different catalytic layouts. In the pyrolysis process, the metal oxides specifically promoted the formation of phenols, ketones, and furans. ZSM-5 was proven to be more effective in producing aromatic hydrocarbons and phenols and in reducing the oxygenated compounds. The combination of MMOs with ZSM-5 effectively improved product distribution by increasing the production of aromatics and phenols. MMOs promoted the aromatics selectivity of undesirable PAHs (70.5%), however, the addition of ZSM-5 to MMOs appeared to reduce and inhibit the formation of PAHs by 0.85%. The highest yield of aromatics was obtained by the layout of the ZSM-5/MMO dual catalysts layout which was 21.6%. Dual catalysts of MMOs and ZSM-5 in separated layout created promising effects in further increasing the production of aromatic hydrocarbons and phenols compared to the mixture of MMOs modified ZSM-5.

An improved parallel reaction model applied to coal pyrolysis

The modeling of pyrolysis can help to understand, predict and optimize many industrial processes. This paper proposes an improved parallel reaction model which tackles the issues of precision and rationality of the popular DAEM (distributed activation energy model). The model was established by optimizing the parameters of sub-reactions, which were estimated via analyzing TG-MS-FTIR (thermogravimetry-mass spectrum-Fourier transform infrared) data of a bituminous coal. The pyrolysis of coal was divided into six sub-reactions corresponding to the primary and secondary pyrolysis at different temperature intervals; including the decomposition of peroxides and carboxylic acids at low temperature, the formation of aliphatic hydrocarbons, aromatics and phenols at medium temperature, and the secondary reactions of aldehydes, ketones and alcohols at high temperature. As heating rate increased, the reaction temperature shifted towards the high region while the overlap of sub-reactions became deeper. The proposed parallel reaction model is bound to provide more accurate predictions of coal pyrolysis and sheds light on the quantitative prediction of fast pyrolysis.