4-ethylphenol Research Articles

Identification of key odorants in honeysuckle by headspace-solid phase microextraction and solvent-assisted flavour evaporation with gas chromatography-mass spectrometry and gas chromatograph-olfactometry in combination with chemometrics.

At present, the identification of honeysuckle aroma depends on experienced tasters, which results in inconsistencies due to human error. The key odorants have the potential to distinguish the different species and evaluate the quality of honeysuckle. Hence, in this study, a more scientific approach was applied to distinguish various honeysuckles. The volatile compounds of different species and parts of honeysuckle were separately extracted by headspace-solid phase microextraction (HS-SPME) and solvent assisted flavor evaporation (SAFE). Compounds with greater volatility such as aldehydes, limonene, γ-terpinene, and terpinolene were preferentially extracted by HS-SPME. As a complementary extraction method to HS-SPME, SAFE was found to recover comparatively more polar compounds such as eugenol, decanoic acid, and vanillin. Subsequently, key odorants with the highest flavour dilution (FD) factors were detected by aroma extract dilution analysis (AEDA). These were benzaldehyde, 4-ethylphenol, decanoic acid, vanillin, 3-methyl-2-butenal, and β-ionone in honeysuckle flowers and γ-octalactone, 4-ethyl phenol, and vanillin in honeysuckle stem. Finally, principal component analysis (PCA) was conducted to analyze not only the key odorants of species and parts of honeysuckle but also their different origins. The results of PCA suggested that the species of honeysuckle contributed much more to variations in aroma rather than their origins. In conclusion, the application of the key odorants combined with PCA was demonstrated as a valid approach to differentiate species, origins, and parts of honeysuckle.

Enhanced production of 4-ethyl phenol from activated carbon catalyzed fast pyrolysis of bagasse with 9,10-dihydroanthracene as a hydrogen donor

A novel way was put forward with 9,10-dihydroanthracene (DHA) as a solid hydrogen donor to improve the selective production of 4-ethyl phenol (4-EP) from catalytic fast pyrolysis (CFP) of bagasse over activated carbon (AC) catalyst. Both pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale CFP experiments were carried out on the 4-EP formation affected by various factors, in order to determine the optimal conditions for 4-EP production. The results indicated that DHA exhibited promising hydrogenation capabilities to improve 4-EP formation. In Py-GC/MS test, the 4-EP reached a maximal yield of 3.21 wt% with its corresponding selectivity of 22.96 % at 350 °C under AC-to-bagasse (AC-to-BA) and DHA-to-bagasse (DHA-to-BA) ratios of 6:1 and 1:5, respectively. Whereas, the maximal 4-EP yield was only 2.18 wt% in the absence of DHA, indicating a yield increase of 47.2 % by DHA. Moreover, lab-scale experiments attained the highest 4-EP yield and the corresponding selectivity of 3.05 wt% and 16.31 % with DHA, compared with the yield of 1.67 wt% without DHA. In addition, the possible hydrogenation mechanism of DHA in facilitating 4-EP formation was revealed.

Bamboo wastes catalytic pyrolysis with N-doped biochar catalyst for phenols products

Biomass catalytic pyrolysis for valuable O-containing chemicals is a promising approach for better utilization of oxygen in biomass resource, where the catalyst, with the properties of green, low cost, high activity and stability, is a critical point. In this study, we proposed a novel and green method to produce phenols through biomass (bamboo wastes) catalytic pyrolysis with N-doped biochar catalyst, which was investigated in a fixed bed reactor to explore the catalytic pyrolysis mechanism of N-doped biochar catalyst. N-doped biochar catalysts, with different nitrogen content and specific surface area, were by products came from biomass N-enriched pyrolysis. Results showed that N-doped biochar catalyst greatly promoted the generation of phenols (reached 82%), especially valuable 4-vinyl phenol with 31% content and 6.65 wt% yield, as well as 16% 4-ethyl phenol with 3.04 wt% yield, based on biomass. It also promoted aromatics formation, while inhibited the generation of O-species and acetic acid with more CO2 and H2O release, thus greatly improved bio-oil quality. Furthermore, N-containing groups in N-doped biochar catalyst showed good stability, while O-containing groups decreased largely. N-doped biochar mainly acted as adsorbent, catalyst, and reactant during catalytic pyrolysis, and the possible catalytic pyrolysis mechanism was proposed based on experiment results and quantum calculations. In conclusion, N-doped biochar catalyst showed excellent catalytic property for biomass catalytic pyrolysis for phenols products.

Hydrotreating of Guaiacol and Acetic Acid Blends over Ni2P/ZSM-5 Catalysts: Elucidating Molecular Interactions during Bio-Oil Upgrading.

Catalytic hydrodeoxygenation (HDO) is an effective technology for upgrading pyrolysis bio-oils. Although, in the past years, this process has been extensively studied, the relevance of the cross-reactivity between the numerous chemical components of bio-oil has been scarcely explored. However, molecular coupling can be beneficial for improving the bio-oil characteristics. With the aim of gaining a better understanding of these interactions, this work investigates the catalytic hydrodeoxygenation of mixtures of two typical components of pyrolysis bio-oils: guaiacol and acetic acid. The catalytic tests were carried out employing a bifunctional catalyst based on nickel phosphide (Ni2P) deposited over a commercial nanocrystalline ZSM-5 zeolite. The influence of both hydrogen availability and temperature on the activity and product distribution, was evaluated by carrying out reactions under different H2 pressures (40–10 bar) and temperatures (between 260 and 300 °C). Using blends of both substrates, a partial inhibition of guaiacol HDO occurred because of the competence of acetic acid for the catalytic active sites. Nevertheless, positive interactions were also observed, mainly esterification and acylation reactions, which could enhance the bio-oil stability by reducing acidity, lowering the oxygen content, and increasing the chain length of the components. In this respect, formation of acetophenones, which can be further hydrogenated to yield ethyl phenols, is of particular interest for biorefinery applications. Increasing the temperature results in an increment of conversion but a decrease in the yield of fully deoxygenated molecules due to the production of higher proportion of catechol and related products. Additional experiments performed in the absence of hydrogen revealed that esterification reactions are homogeneously self-catalyzed by acetic acid, while acylation processes are mainly catalyzed by the acidic sites of the zeolitic support.

Cellar Temperature Affects Brettanomyces bruxellensis Population and Volatile Phenols Production in Aging Bordeaux Wines

Brettanomyces bruxellensis is a spoilage yeast particularly dreaded in red wines, where it produces volatile phenols with sensory properties that lead to wine spoilage. The development of this yeast often occurs during wine aging, especially during the summer. We show that in the Bordeaux region, the temperatures of some cellars rise significantly in July, August, and September. This greatly increases the growth rate of B. bruxellensis strains in both permissive and more unfavorable wines. Therefore, although temperature does not affect the specific formation rate of ethyl phenol, raising the wine temperature from 2 to 6°C makes volatile phenols appear both earlier and faster, regardless of the wine or the yeast strain present. Closer control of active yeast populations and closer monitoring of aging wines is thus essential in the summer, particularly in cellars with poor temperature regulation.

Synthesis of Ethyl Phenol over Modified HZSM-5 Catalyst in a Fixed Bed Reactor

Abstract The selective synthesis of p-ethyl phenol in vapor phase alkylation of phenol with ethanol was investigated in a fixed bed flow reactor on cerium modified zeolite CeZSM5 at temperature 693 K. A series of cerium modified zeolite such as Ce4ZSM54, Ce6ZSM56, Ce8ZSM58, Ce10ZSM5 were prepared by modifying with 4 %, 6 %, 8 % and 10 % ceric ammonium nitrate solution respectively. HZSM-5 zeolite exchanged with 10 % cerium nitrate solution was proved to be the best of all the catalyst used. The modified catalyst was further characterized by SEM, XRD and EDS. Phenol reacted with ethanol to form ethylphenyl ether by O-alkylation, and p-ethylphenol- and o-ethylphenol isomers by C-alkylation; secondary products were m-ethylphenol and dialkylated compounds. Reactions were carried out in the temperature 623 K–693 K, reactant mole ratio 0.2–0.5 over modified HZSM-5 zeolite. The optimum operating condition for maximum selectivity of p-ethyl phenol were EtOH to phenol mole ratio, 4:1; temperature, 623 K; space-time, 10.2 kg h/kmol and 1 atm pressure. A detailed kinetic study was carried out for the ethyl phenol synthesis reaction. From the product distribution pattern, a kinetic model for the reactions was proposed following the Langmuir–Hinshelwood approach. The kinetic and adsorption parameters of the rate equation were determined by non-linear regression analysis. From the kinetic analysis of the experimental data, the apparent activation energy for the reaction was determined as 43.27 kJ/mol.

Catalytic depolymerization of organosolv lignin to phenolic monomers and low molecular weight oligomers

The lignin-first strategy provides significant potential for producing value-added phenolics and high-quality biofuels. In this contribution, stepwise extraction and depolymerization of lignin in corncob residue towards the production of phenolic monomers, lignin-derived dimers and trimers was investigated. H2O/n-butanol (4:6, v/v) co-solvent could extract 87.1% of lignin in corncob residue, retaining a high-purity (86.0%) cellulose pulp. Ni/HZSM-5 catalysts with different Ni loadings were prepared and applied for further degradation of organosolv lignin. Over 5% Ni/HZSM-5, the highest yield of phenolic monomer was 19.5% with the selectivity of 66.7% towards 4-ethyl phenols (4-ethyl phenol and 4-ethyl guaiacol) at 300 °C, and liquid products with higher heating value (HHV) of 29.2 MJ kg−1 were obtained. The 5% Ni/HZSM-5 catalyst promoted the cleavage of intramolecular β-O-4 and Cβ-Cγ linkages, resulting in substantially decreased weight-average molecular weight (Mw)/number-average molecular weight (Mn) of the organosolv lignin from 2541/1064 Da to 562/391 Da, which implied the degradation of high-Mw oligomers to dimers and trimers. The catalyst also contributed to the hydrogenation of CαCβ bonds in unsaturated intermediates (coniferyl alcohol and coumaryl alcohol). The possible cleavage mechanism for the degradation of lignin-derived oligomers was also proposed.

Selective depolymerization of lignin catalyzed by nickel supported on zirconium phosphate

A novel process for efficient para ethyl phenol production was provided via the selective cleavage of pCA8 linkage of lignin.

Evolution of the volatile flavor compounds of Chinese horse bean-chili-paste

The production of Chinese horse bean-chili-paste (CHCP) involves three fermentation phases: a chili-to-moromi phase, a horse bean-to-meju phase and a moromi-meju mixed fermentation phase. In consideration of raw materials and fermentation phases, the evolution of key volatile flavor compounds in CHCP were investigated in this study by using GC-MS, olfactometry and principal component analysis. Results showed that there were 22 key flavor compounds in CHCP. Among which, (E)-2-nonenal, nonanal and 3-methyl-1-butanol were primarily from chili, and 1-octen-3-ol was from horse bean. Ethyl decanoate and linalool were mainly formed during the chili fermentation, while ethyl isobutyrate, phenylethyl alcohol and benzene acetaldehyde were found closely related to the horse bean-to-meju process. The mixed fermentation of chili moromi and horse bean meju was significant for the accumulation of 13 key compounds, including 2-methyl-1-butanol, 3-methyl butyraldehyde, 2-methyl butyraldehyde, ethyl isovalerate, ethyl hexanoate, ethyl benzoate, ethyl phenylacetate, guaiacol, 4-ethyl phenol, 4-ethyl guaiacol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF) and 3-(methylthio) propanal. Results are conducive to understand the accumulation mechanism of CHCP flavor compounds and promote the quality improvement.

Testing the Sensitivity of Potential Panelists for Wine Taint Compounds Using a Simplified Sensory Strategy

The odor detection threshold (ODT) of a compound is the lowest concentration at which individuals can reliably perceive a difference between a sample and its corresponding control, with 50% performance above chance. Wine is a complex matrix, and ODTs used in studies on wine can be based on inappropriate matrices and informal sensory methodologies. Formal studies confirming ODTs in wine are relatively scarce in the literature, and are complex and expensive to carry out. In this study, the sensitivity of panelists to previously published ODTs for five compounds: Guaiacol, o-cresol and 4-ethyl phenol, 3-isobutyl-2-methoxypyrazine (IBMP), and 2,4,6-trichloroanisole (TCA) associated with off-flavor/taint issues in wine, was investigated. The study was carried out in partially de-aromatized young Shiraz wine (unwooded) using a simplified version of the formal sensory approach. A triangle test in triplicate was carried out with 34 panelists, at the ODT for each compound, in one day. The study explored whether previous training affected panelists’ sensitivity for threshold differences. Results showed that samples spiked with volatile phenols were significantly different (p = 0.01) to controls. The spiked TCA and IBMP samples were not significantly different from the control in either case. Judges were better able to detect compounds if they had prior experience or training in wine evaluation. Despite some limitations, this pragmatic approach may be useful when carrying out sensory studies with fairly limited resources and within tight timelines, as it provides helpful information on panel members and detection thresholds for a specific matrix.

Catalytic fast pyrolysis of sugarcane bagasse using activated carbon catalyst in a hydrogen atmosphere to selectively produce 4-ethyl phenol

Activated carbon (AC) prepared by physical activation with steam (named as AC-H2O) was employed for catalytic fast pyrolysis of bagasse in a hydrogen atmosphere to selectively produce 4-ethyl phenol (4-EP), a valuable phenolic compound. Lab-scale fast pyrolysis experiments were conducted to quantitatively determine the pyrolytic products and investigate several factors on the 4-EP production, including pyrolysis atmosphere, AC type, catalytic pyrolysis temperature, and AC-to-bagasse ratio. The results indicated that the AC-H2O (activated by H2O) catalyst exhibited much better performance on 4-EP production than other ACs prepared by different activation methods. Compared with the inert atmosphere, the presence of hydrogen atmosphere could significantly promote the 4-EP formation with the yield increase by over 36%. The maximal 4-EP yield of 3.55 wt% with the selectivity of 17.42% was obtained under AC-to-bagasse ratio of 1.5 at 330 °C. In addition, the gas product produced by the pyrolysis process could be recycled to provide a hydrogen atmosphere without an additional hydrogen supply.

Effect of Spanish-style processing steps and inoculation with Lactobacillus pentosus starter culture on the volatile composition of cv. Manzanilla green olives

The effects of the main steps of Spanish-style processing (alkaline treatment and fermentation) on the volatile composition of cv. Manzanilla green olives were studied. Both spontaneous and controlled fermentations were considered. In the latter case, a Lactobacillus pentosus strain from green olive fermentation brine was used as starter culture. The volatile profile was determined by headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS). Most of the volatile compounds detected in fresh olives decreased or were undetected after alkaline treatment, while several compounds (mostly acetic acid, 2-methylbutanoic acid, and ethanol) were formed as a result of this treatment. Over 50 new volatile components, mostly esters and phenols, appeared as a result of fermentation. The most outstanding finding was a considerable increase in 4-ethyl phenol (almost 100-fold increase) in inoculated olives compared to the uninoculated product. However, a sensory panel did not find significant differences in odor perception.

Inhibition mechanism of the radical inhibitors to alkaline degradation of anion exchange membranes

We employed four radical inhibitors to investigate their influences on the degradation of poly (4-vinylbenzyl chloride-styrene) based anion exchange membranes (AEMs) in alkaline solutions. It is found that the presence of the radical inhibitors could effectively restrain the nucleophilic attack of hydroxide ions to the AEMs according to the conductivity measurements, especially the one p-ethyl phenol (PEP), which could significantly protect the AEMs against the attack. More evidences including water uptake, swelling ratio as well as FT-IR analysis further proved this phenomenon by comparison those properties of the membranes before and after the stability test in 8 M KOH at 80 °C for 24 h. According to the 1H NMR spectra, the quaternary ammonium groups of the AEMs were mainly degraded into tertiary amines in the hot alkaline solutions; while in the presence of PEP, this degradation was restrained and the quaternary ammonium groups maintained by reaction with PEP. Fenton test results further indicated that high oxidative stability of the AEMs benefited from the presence of a small amount of PEP, which could reduce the generation of the oxidants. Thus an inhibition reaction mechanism of the radical inhibitors preventing the AEMs from alkaline degradation is proposed.

Shape selectivity vapor-phase conversion of lignin-derived 4-ethylphenol to phenol and ethylene over acidic aluminosilicates: Impact of acid properties and pore constraint

Selective dealkylation of alkylphenols, the opposite reaction of the more commonly studied phenol alkylation, may represent an important reaction in the production of base chemicals like phenol and olefins from fossilized and raw lignocellulosic matter. This study reports the first thermodynamics and kinetics studies of the vapor-phase conversion of ethylphenol (EP) over acidic γ-Al2O3, amorphous (ASA) and crystalline aluminosilicates (like ferrierite, ZSM-22, ZSM-5, beta, and USY) in the absence of hydrogen and noble metals, as a way to produce phenol and ethylene. The reaction was studied deliberately in presence of steam to get stable time on stream catalysis. The thermodynamic analysis shows an endothermal EP conversion to phenol and ethylene, favoured at high reaction temperature, while isomerisation, disproportionation and transalkylation are thermodynamically preferred at low temperature. The kinetic study examines the role of the catalytically active sites; it reveals the importance of site constraint on the activity, selectivity and stability, and shows the complex temperature dependency of the dealkylation. Both Brønsted and Lewis acid sites are active, but multifactor dependency (such as acid strength and site accessibility) complicates the establishment of simple quantitative relationships with the acid type. EP does not enter the micropores of ferrierite and ZSM-22, as suggested by adsorption experiments. Kinetics without significant diffusion limitations were obtained with ZSM-5, beta and USY. Thus, in absence of intracrystalline diffusion limitation (as verified by calculations using reported effective diffusivities, and substantiated by a comparably high apparent activation energy for all zeolites), the increased reaction turnover rate with increasing pore size from medium to large pore zeolites is largely explained by a change in reaction pathway (from monolecular to bimolecular) to convert EP to phenol and ethylene. A pathway proceeding through fast thermodynamically favourable bimolecular reactions occurs in the spatially non-constrained pores and crystal surface, whereas monomolecular reactions take place in the micropores of ZSM-5. Despite the lower rate, the selectivity over ZSM-5 strongly benefits from active site confinement, being responsible to achieve quantitative formation of phenol and ethylene from ethylphenol. The excellent performance of ZSM-5 thus accords with its shape selective property that avoids undesired side reactions such as the sterically demanding bimolecular reactions like disproportionation, transalkylation and C-C cracking, and severe cokes formation.

Production of renewable alkyl-phenols from catalytic pyrolysis of Douglas fir sawdust over biomass-derived activated carbons

The catalytic conversion of Douglas fir sawdust into bio-phenols on activated carbons (AC) obtained by chemical activation of corn stover with H3PO4 was investigated. Taguchi experimental design was used to optimize the preparation of AC using microwave assisted pyrolysis. Based on an overall consideration of AC yield, bio-oil yield, and phenols content, the optimized conditions were phosphoric acid to biomass ratio of 0.8, microwave power of 600 W and reaction time of 20 min. The bio-oils were rich in phenolic compounds (up to 90 area %) that mainly comprised phenol, methyl and ethyl phenol. During the catalytic pyrolysis of biomass with AC, phenolic compounds could either be derived from decomposition of lignin, followed by deoxygenation, or derived from furfurals, which were degradation products of carbohydrates. The catalytic activities of ACs were mainly owing to the well-developed porosity and abundant acidic surface functional groups. The porous structures of ACs were characterized by N2 isotherms, showing a strong dependence on the acid impregnation ratio and microwave irradiation power. The presence of acidic phosphoric-containing surface functional groups was confirmed by SEM/EDX, FTIR and NH3-TPD.

Effect of kaolin silver complex on the control of populations of Brettanomyces and acetic acid bacteria in wine.

In this work, the effects of kaolin silver complex (KAgC) have been evaluated to replace the use of SO2 for the control of spoilage microorganisms in the winemaking process. The results showed that KAgC at a dose of 1g/L provided effective control against the development of B. bruxellensis and acetic acid bacteria. In wines artificially contaminated with an initial population of B. bruxellensis at 104 CFU/mL, a concentration proven to produce off flavors in wine, only residual populations of the contaminating yeast remained after 24days of contact with the additive. Populations of acetic bacteria inoculated into wine at concentrations of 102 and 104CFU/mL were reduced to negligible levels after 72h of treatment with KAgC. The antimicrobial effect of KAgC against B. bruxellensis and acetic bacteria was also demonstrated in a wine naturally contaminated by these microorganisms, decreasing their population in a similar way to a chitosan treatment. Related to this effect, wines with KAgC showed lower concentrations of acetic acid and 4-ethyl phenol than wines without KAgC. The silver concentration from KAgC that remained in the finished wines was below the legal limits. These results demonstrated the effectiveness of KAgC to reduce spoilage microorganisms in winemaking.

High alkaline resistance of benzyl-triethylammonium functionalized anion exchange membranes with different pendants

Polymers were synthesized by polymerization of 4-vinylbenzyl chloride with three kinds of aromatic monomers, respectively. Quaternization of these polymers with triethylamine were performed to fabricate associated anion exchange membranes (AEMs) possessing different pendants. The obtained AEMs showed excellent stability in alkaline solutions at elevated temperature and exhibited conductivities of 32.6–39.5 mS cm−1 in water at 80 °C. In particular, the AEM having a pendant of p-ethyl phenol could maintain the initial conductivity of 89% after immersed in 1 M KOH at 80 °C for 1000 h. Even soaked in 8 M KOH solution at 80 °C for 24 h, this AEM still exhibited a conductivity of 26.4 mS cm−1 at 80 °C, about 80% of its original conductivity was remained. However, the rest of prepared AEMs showed significant decline in conductivity. We studied the tolerance of the prepared AEMs to 8 M KOH at 80 °C in the presence of p-ethyl phenol with a concentration of 0.025 M. It is found that the stability of all the AEMs was obviously enhanced, about 70–90% of the initial conductivity was retained. This result suggests an effective strategy to improve the alkaline stability of the AEMs.

Spoilage potential of brettanomyces bruxellensis strains isolated from Italian wines

Brettanomyces bruxellensis is an important wine spoilage agent. In this study a population of Brettanomyces strains isolated from Italian wines was thoroughly investigated to evaluate adaptability to wine conditions and spoilage potential. The presumptive isolates of Brettanomyces were identified at species level with 26S rRNA gene sequencing and species-specific PCR, and subsequently subjected to analysis of intra-species variability through the study of intron splice sites (ISS-PCR). Although, some strains were tracked in wines from different regions, extensive genetic biodiversity was observed within the B. bruxellensis population investigated. All strains were evaluated for their growth ability in the presence of ethanol, high sugar content, low pH, different temperatures and sulphur dioxide, using optical density and flow cytometry measurement. The ability of yeasts to produce ethyl phenols in red wines with different chemical compositions was evaluated by means of high performance liquid chromatography with electrochemical detection (HPLC-ECD). The results highlighted wide variability in B. bruxellensis in response to wine limiting factors and in terms of the accumulation of ethyl phenols. As regards this last aspect, the differences found among strains were closely related to chemical composition of wine and strain resistance to environmental stress factors, making a priori evaluation of risk of wine alteration quite difficult. These results suggest that strategies for the control of Brettanomyces should be tailored on the basis of strain distribution and wine characteristics.

Erratum: Carrasco-Sánchez, V.; et al. Removal of 4-Ethylphenol and 4-Ethylguaiacol with Polyaniline-Based Compounds in Wine-Like Model Solutions and Red Wine. Molecules 2015, 20(8), 14312-14325.

The authors wish to make the following change to their paper [1]. The Acknowledgments sectionis incorrect in the published paper. The correct Acknowledgments should be as follows:Postdoctoral Fondecyt Project 3140295, Proyecto Anillo (Integracion de la BiologiaEstructural al desarrollo de la Bionanotecnologia, ACT 1107), Innova Chile CORFO(Grant FCR-CSB 09CEII-6991), Programa de insercion y atraccion CONICYT-79090038,and PIEI-QUIBIO (UTalca) are acknowledged. A.J acknowledges FONDECYT 11130087.We apologize for any inconvenience caused to the readers by this mistake.

The effects of potassium on distributions of bio-oils obtained from fast pyrolysis of agricultural and forest biomass in a fluidized bed

Potassium, due to its strong catalytic effects on biomass pyrolysis vapors, has great influence on the components of the obtained bio-oil. In this work, fast pyrolysis of acid washed and potassium salts impregnated feedstocks (camphor branch, corn cob and walnut shell) were carried out in a fluidized bed. The effects of potassium and the ash in biomass on yields and selectivities of bio-oil compounds were studied. The results showed that the walnut shells yielded the greatest amount of phenol and acids. Potassium promoted the conversion of large molecular compounds (such as levoglucosan) to furans. The existence of potassium reduced the yield of aldehydes and enhanced that of furfural. With the assistance of potassium, the selectivity of monophenols (phenol, methyl phenol, dimethyl phenol, etc.) decreased significantly to around half, while that of polyphenols (ethyl phenol, 2-allylphenol, 4-(2-propenyl)-phenol, 2-allyl-4-methylphenol, etc.) increased obviously. Finally, a possible reaction pathway indicating potassium influences on biomass pyrolysis was proposed according to the experimental results.