Porous silica nano-flowers stabilized Pt-Pd bimetallic nanoparticles as heterogeneous catalyst for efficiently synthesizing guaiacol from 2-methoxycyclohexanol

Porous silica nano-flowers(KCC-1)immobilized Pt-Pd alloy NPs(Pt-Pd/KCC-1)with different mass ratios of Pd and Pt were successfully prepared by a facile in situ one-step reduction,using hydrazinium hydroxide as a reducing agent.The as-synthesized silica nanospheres possess radial fibers with a distance of 15 nm,exhibiting a high specific surface area(443.56 m^(2)·g^(-1)).Meanwhile,the obtained Pt-Pd alloy NPs are uniformly dispersed on the silica surface with a metallic particle size of 4-6 nm,which exist as metallic Pd and Pt on the surface of monodisperse KCC-1,showing the transfer of electrons from Pd to Pt.The as-synthesized 2.5%Pt-2.5%Pd/KCC-1 exhibited excellent catalytic activity and stability for the continuous dehydrogenation of 2-methoxycyclohexanol to prepare guaiacol.Compared with Pt or Pd single metal supported catalysts,the obtained 2.5%Pt-2.5%Pd/KCC-1 shows 97.2%conversion rate of 2-methoxycyclohexanol and 76.8%selectivity for guaiacol,which attributed to the significant synergistic effect of bimetallic Pt-Pd alloy NPs.Furthermore,turn over frequency value of the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs achieved 4.36 s^(-1),showing higher catalytic efficiency than other two monometallic catalysts.Reaction pathways of dehydro-aromatization of 2-methoxycyclohexanol over the obtained catalyst are proposed.Consequently,the obtained 2.5%Pt-2.5%Pd/KCC-1 NPs prove their potential in the dehydrogenation of 2-methoxycyclohexanol,while the kinetics and mechanistic study of the dehydrogenation reaction over the catalyst in a continuous fixed-bed reactor may provide valuable information for the development of green,outstanding and powerful synthetic pathway of guaiacol.

Photochemical Production of Methyl Halides with Guaiacol as the Precursor

Methyl halides are crucial trace greenhouse gases in the atmosphere,playing a significant role in global climate change and the atmospheric environment.This study investigated the photochemical production of methyl halides in an artificial seawater system using guaiacol as a precursor through laboratory simulation experiments.The influences of various environmental factors,including illumination time,radiation wavebands,illumination intensity,concentrations of guaiacol and halide ions(X^(-)),Fe^(3+),salinity,dissolved oxygen(DO),and pH value on the photochemical production of methyl halides were examined.We demonstrated that increased illumination intensity and duration promote the photochemical production of methyl halides,with a notable enhancement under UV-B radiation.Guaiacol and halide ions were identified as key precursors,and their high concentrations facilitated the formation of methyl halides.Additionally,different types of halide ions exhibited a competitive relationship in producing methyl halides.The study found that an increase in pH inhibited the photochemical formation of CH_(3)I due to the reaction between OH^(-)and·CH_(3).Dissolved oxygen was found to inhibit the photochemical formation of CH3I while promoting the formation of CH_(3)Cl.Conversely,an appropriate concentration of Fe^(3+)enhanced the photochemical production of methyl halides.Field observations indicated a high photochemical production of methyl halides in the natural waters near Qingdao’s coastal area,likely due to the high concentration of dissolved organic matter(DOM),which supports photochemical reactions.Furthermore,the photochemical production of methyl halides in natural seawater was significantly higher than in dark conditions,underscoring the importance of illumination in promoting these photochemical processes in seawater.

Catalytic conversion of guaiacol to alcohols for bio-oil upgrading

Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio（H/Ceff factor） in bio-oil,and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided catalysts. Effects of metal composition,reaction temperature,and hydrogen pressure on conversion and selectivity were investigated systematically. Among various compositions of catalysts,Ni Co/CNT exhibited best performance of guaiacol conversion with higher selectivity towards desired alcohols with higher H/Cefffactor. The reaction pathways of guaiacol in aqueous were proposed based on the product analyzed.Results show that metal composition and temperature have great effects on the conversion of guaiacol and the yields of desired products.

Dietary guaiacol improves the growth of juvenile abalone,Haliotis discus hannai Ino

We conducted a preliminarily study on the effects of dietary guaiacol on growth performance of abalone, Haliotis discus hannai Ino. Seven semi-purified diets were formulated with graded levels of guaiacol （0, 5, 10, 50, 100, 500, and 1 000 mg kgl）. Abalone （initial weight： 0.29 ± 0.01 g; initial shell length： 8.55 ± 0.27 mm） were fed with these diets in a re-circulated water system for 152 days. Guaiacol significantly improved the specific growth rate （SGR） （P〈0.05）; excessive dietary guaiacol （1 000 mg kg1） led to significantly high mortality （P〈0.05）, and lipid content in the soft body increased significantly after dietary guaiacol （P〈0.05）. Activities of catalase and phenoloxidase （PO） in the viscera were significantly stimulated by dietary guaiacol （P〈0.05）. Broken-line analysis based on SGR indicated that the minimum dietary guaiacol for the optimal growth of juvenile abalone is 15.43 mg ·kg^-1.

“H_(2)-free” demethoxylation of guaiacol in subcritical water using Pt supported on N-doped carbon catalysts:A cost-effective strategy for biomass upgrading

"H_(2)-free" HDO is a revolutionary route to circumvent the limitations of H_(2)-fed HDO reactors for biomass upgrading.This work demonstrates the viability of this economically appealing route when an adequate catalyst is implemented.Herein,we have developed a new family of Pt catalysts supported on N-doped activated carbons for the H_(2)-free HDO process of guaiacol.Several N-donors have been used to tune the catalyst’s structural and electronic properties.As a general trend,the N-promoted samples are more selective towards oxygen-depleted products.The best performing material,namely Pt/PANI-AC reached outstanding guaiacol conversion values-ca.75% at 300℃ while displaying reasonable stability for multiple recycling operations.The advanced performance is ascribed to the modified electronic and acid-base properties which favor guaiacol activation and C-O cleavage,as well as the excellent dispersion of the Pt nano particles.

Investigation on molar heat capacity, standard molar enthalpy of combustion for guaiacol and acetyl guaiacol ester

The molar heat capacities(C_p) of guaiacol(CAS 90-50-1) and acetyl guaiacol ester(AGE, CAS 613-70-7) were determinated from 290 K to 350 K by differential scanning calorimetry(DSC), and expressed as a function of temperature. Two kinds of group contribution models were used to estimate the molar heat capacities of both guaiacol and AGE, the average relative deviation is less than 10%. The standard molar enthalpies of combustion of guaiacol and AGE were- 3590.0 k J·mol^(-1)and- 4522.1 k J·mol^(-1) by a precise thermal isolation Oxygen Bomb Calorimeter. The standard molar enthalpies of formation of guaiacol and AGE in a liquid state at298.15 K were calculated to be- 307.95 k J·mol^(-1) and- 448.72 k J·mol^(-1), respectively, based on the standard molar enthalpies of combustion. The thermodynamic properties are useful for exploiting the new synthesis method, engineering design and industry production of AGE using guaiacol as a raw material.

Selective hydrodeoxygenation of guaiacol to cyclohexanol using activated hydrochar-supported Ru catalysts

Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydrodeoxygenation of guaiacol,a lignin-derived monomer,can produce cyclohexanol,a nylon precursor,in a carbon-negative and environmentally friendly manner.This study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective hydrochar.Highly selective cleavage of C_(ary)-O bonds was achieved under mild conditions(160°C,0.2 MPa H_(2),and 4 h),and alkali activation further improved the catalytic activity.Various characterization methods revealedthat hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion.X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium,indicating the effective regulation of interaction between active sites and supports.This synergistic approach used in this study,involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol,indicated the comprehensive and sustainable utilization of biomass resources.

Molecular modeling and spectroscopic studies on the binding of guaiacol to human immunoglobulin

The fluorogenic property of guaiacol was exploited for the first time to analyze the interaction with target protein as a probe by molecular modeling, fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. Molecular docking was performed to reveal the possible binding mode or mechanism and suggested that guaiacol can strongly bind to human immu- noglobulin (HIgG). It is considered that guaiacol binds to HIgG mainly by a hydrophobic interaction and there are two hydrogen bond interactions between the drug and the residues LEU 80 and ASP 65, which is in good agreement with the results from the experimental thermodynamic parameters (the enthalpy change △H0 and the entropy change △S0 were calculated to be 65.55 kJ·mol-1 and 132.95 J·mol-1·K-1 according to the Vant’ Hoff equation). Data obtained by the fluorescence spectroscopy indicated that binding of guaiacol with HIgG leads to dramatic enhancement in the fluorescence emission intensity along with significant occurrence of efficient Frster resonance energy transfer (FRET) from the residue of HIgG to the protein bound guaiacol. From the low value of fluorescence anisotropy (r = 0.06), it is argued that the probe molecule is located in the motionally unrestricted environment of the protein. The alterations of protein’s secondary structure in the presence of guaiacol in aqueous solution were quantitatively calculated by the evidences from FT-IR and CD spectroscopes.

Highly selective catalytic hydrodeoxygenation of guaiacol to cyclohexane over Pt/TiO2 and NiMo/Al2O3 catalysts

Abstract Catalysts Pt/TiO2 and NiMo/Al2O3 are highly active and selective for the hydrodeoxygenation of guaiacol in a fixed bed reactor at 300℃ and 7.1 MPa, leading to the hydrogenation of aromatic ring, followed by demethylation and dehydroxylation to produce cyclohexane. For a complete hydrodeoxygenation of guaiacol, metal sites and acid sites are required. NiMo/Al2O3 and Pt/ Al2O3 are more active and selective for cyclohexane formation as compared with Pt/TiO2 at 285 Al2O3 and 4 MPa. However, Pt/TiO2 is stable while the other two catalysts deactivate due to the nature and amount of coke formation during the reaction.

La_(2)O_(3)-promoted Ni/H-ZSM-5 catalyzed aqueous-phase guaiacol hydrodeoxygenation to cyclohexanol

Hydrodeoxygenation(HDO)of renewable lignin-derived biomass in aqueous-phase to produce high value-added products is of great significance.However,developing new catalysts with high activity and excellent stability in an aqueous phase faces considerable challenges.Rare earth doping can effectively regulate the water exchange rate constant(WERC)value of the catalyst and play an important role in promoting the hydrolysis of ether bonds.Therefore,in this paper the bimetallic supported catalyst Ni-La_(2)O_(3)/H-ZSM-5 doped with rare earth metal La_(2)O_(3)was prepared,and used to catalyze the conversion of the lignin model co mpound guaiacol to cyclohexanol in the aqueous phase.The co nversion of guaiacol catalyzed by 10Ni-3La_(2)O_(3)/H-ZSM-5 reaches 100%,and the selectivity of the product cyclohexanol is 85%.A series of characterizations illustrate that the doping of La_(2)O_(3)causes the electron transfer between La_(2)O_(3)-Ni and changes the distribution of Ni,and a strong metal carrier interaction occurs between the bimetallic Ni-La_(2)O_(3)and H-ZSM-5.This can effectively promote the hydrolysis of the C-O ether bond in guaiacol and significantly improve the activity of the catalyst.The possible catalytic reaction mechanism of Ni-La_(2)O_(3)/H-ZSM-5 catalytic conversion of guaiacol was proposed.

Selective production of guaiacol from black liquor:Effect of solvents

Lignin is generated as a waste biomass from pulp and paper industry.The majority of kraft lignin is currently combusted as a low-grade energy source.Lignin valorization has been considered a feasible option to sustainable production of chemicals and liquid fuels in the long run.This study reports a novel thermolysis process that selectively converts black liquor lignin into guaiacol and its derivatives in highboiling-point hydrocarbon solvents:n-hexadecane(n-H)and 1-methyl naphthalene(1-MN).The operating pressure for lignin thermolysis in n-H and 1-MN is much lower than those in lignin liquefaction with low-boiling-point solvents,such as water,methanol,and ethanol.1-MN performed better than n-H in terms of lignin conversion and liquid yield.The liquid products were 56 wt%and 24 wt%for 1-MN and n-H as solvent respectively.Reaction temperature and reaction time rotating were investigated.Low temperature and short reaction time are favorable for generating Guaiacol.Compared to 1-MN as solvent,n-H promotes the production of guaiacol.The reaction mechanisms of lignin depolymerization to chemicals in different solvents were proposed.Solvent chemical properties and H abstraction processes from solvents play a key role in the selectivity of guaiacol.

愈创木酚与环戊醇烷基化-加氢脱氧制备高密度低冰点生物航油

以木质纤维素为原料合成高密度低冰点生物航油,可以实现绿色低碳发展。报道了一种以木质素衍生物愈创木酚和半纤维素衍生物环戊醇为原料,经过烷基化和加氢脱氧制备高密度低冰点燃料的工艺路线。筛选出硅铝比为100的USY分子筛作为烷基化反应的催化剂,在优化工况下愈创木酚的转化率可达到97.7%,双环和三环产物的总产率为93.9%。筛选出HZSM-5和Pt/C的组合催化剂催化烷基化产物加氢脱氧,在260℃反应12h,可以实现烷基化产物96.4%的转化率,双环烷烃的产率为27.7%,三环烷烃的产率为63.8%。加氢脱氧终产物的密度为0.89 g/mL,冰点低于-65℃。该研究为木质纤维素衍生物合成高性能喷气燃料提供了一种简单高效的方法。

蒙古栎叶提取物和木醋液酚类物化感作用

以蒙古栎叶与木醋液为原料,采用气相色谱-质谱(GC-MS)分别分析其成分,结果表明,蒙古栎叶提取物相对含量较高的成分,2,3-二甲基-2-环戊烯-1-酮(13.49%)、2-甲基苯酚(9.22%)等。木醋液相对含量较高的成分,愈创木酚(28.27%)、苯酚(7.78%)、对甲酚(4.97%)、2,3-二甲基-2-环戊烯-1-酮(4.93%)等。种子萌发实验表明,相比对照组,叶提取物稀释50、100、200、400倍对小白菜发芽率抑制显著,稀释50、100、200、400、800、1600倍对芥菜发芽率抑制显著;木醋液稀释50倍对芥菜发芽率抑制显著,叶提取物与木醋液中所含酚类物对种子发芽率有一定抑制作用。

氯化胆碱/乳酸/愈创木酚三元共熔溶剂提取灵芝多糖的工艺及其抗氧化活性研究

本研究采用氯化胆碱/乳酸/愈创木酚三元共熔溶剂(DES)来提取灵芝多糖(GLPs),优化DES溶剂提取灵芝多糖的工艺参数,采用傅里叶变换红外光谱(Fourier Transform Infrared Spectroscopy,FT-IR)和凝胶渗透色谱(Gel Permeation Chromatography,GPC)对GLPs结构进行了表征,并研究其体外抗氧化活性,最后,采用密度泛函理论初步研究了DES提取GLPs的分子机制。结果表明,在含水量为50%、提取温度为80℃、提取时间为1 h、料液质量体积比为1:30 g/mL的条件下,GLPs得率达9.20%±0.27%。FT-IR和GPC分析表明,4000~500 cm-1区域GLPs具有典型的多糖结构,GLPs的数均分子量为8057 Da,多分散系数为1.6。体外抗氧化活性测试显示,当GLPs质量浓度为5 mg/mL时,其总还原力为0.67±0.04。此外,GLPs对DPPH、OH和ABTS+自由基的清除能力的IC50值分别为2.366、6.179和2.440 mg/mL。密度泛函理论模拟分析表明,DES与葡萄糖之间的结合能为65.29 kcal/mol,远高于水与葡萄糖之间的结合能(20.38 kcal/mol),DES提取多糖是通过三重氢键相互作用来实现的。研究成果从分子水平上阐明了DES提取GLPs效果优于传统热水提取方法的内在机制。

高效液相色谱波长切换法同时测定复方愈创木酚磺酸钾口服溶液中6种防腐剂

建立高效液相色谱波长切换法同时测定复方愈创木酚磺酸钾口服溶液中苯甲酸、山梨酸、羟苯甲酯、羟苯乙酯、羟苯丙酯、羟苯丁酯6种防腐剂含量。采用Waters XSelect HSS T3(250 mm×4.6 mm,5μm)色谱柱,甲醇作为流动相A,0.1%乙酸铵溶液(用乙酸调节pH值至4.5)作为流动相B,梯度洗脱,流量为1.0 mL/min,柱温为40℃,检测波长分别为226、256 nm,进样体积为10μL。6种防腐剂在质量浓度0.2~28.6μg/mL内与色谱峰面积呈良好线性关系,相关系数均为0.9999,精密度试验测试结果的相对标准偏差为0.1%~0.6%,样品加标平均回收率为98.8%~102.2%。该方法操作简单,专属性强,准确度高,重复性好,可用于复方愈创木酚磺酸钾口服溶液的防腐剂检测,为生产企业的处方、生产工艺和质量标准的把控提供参考作用。

HPLC法测定复方愈创木酚磺酸钾口服溶液中盐酸异丙嗪相关杂质的研究

目的:建立复方愈创木酚磺酸钾口服溶液中盐酸异丙嗪有关物质的测定方法。方法:采用高效液相色谱法,以十八烷基硅烷键合硅胶为固定相,以0.01 mol·L^(-1)磷酸氢二铵溶液(磷酸调节pH值至7.0)-乙腈为流动相,梯度洗脱,流速1.0 mL·min^(-1),柱温30℃,样品盘温度10℃,检测波长249 nm。结果:盐酸异丙嗪和杂质A、B、C、D分别在0.1155~2.3104、0.1009~2.0180、0.1169~2.3383、0.1097~2.1948、0.4169~20.8473μg·mL^(-1)呈良好线性关系,相关系数r均为0.9999,杂质A、B、C、D平均回收率分别为96.2%、96.3%、100.1%、100.9%(n=6)。结论:该方法操作简便,专属性和重复性好,结果准确,可作为复方愈创木酚磺酸钾口服溶液中盐酸异丙嗪有关物质的测定方法。

水中苯胺类化合物的分光光度法测定

提出 3种测定水中苯胺类化合物的分光光度法。在氢氧化钠介质 (pH =1 2 .2 )中 ,邻甲氧基苯酚、8 羟基喹啉和 1 萘酚均可与苯胺形成偶氮化合物。它们的最大吸收波长分别位于 45 2、482和 497nm处。与传统的N (1 萘基 )乙二胺光度法相比 ,这 3种方法测定苯胺更方便、快速、灵敏 ,线性范围更宽 ;它们的检出下限分别为 8.6、1 0、1 4μg L ;线性范围分别为 0～ 5 .6、0～ 4.8和 0～ 3 .2mg L。这 3种方法用于测定环境水样中的苯胺类化合物 ,均获得了满意的结果。

在Al-P-Ti-Si-O催化剂上由甲醇和邻苯二酚合成愈创木酚的研究

采用非均匀沉淀法制备了 Al1 P1 .3 0 Tia Sib( a=0～ 0 .5 1 ,b=0～ 0 .90 )复合催化剂 ,研究了邻苯二酚与甲醇在该催化剂上的气相 o-甲基化反应 .结果表明 ,催化剂组成、相结构和表面性质对催化剂的活性和选择性有很大影响 .其中 Al1 P1 .3 0 Ti0 .3 0 Si0 .1 7催化剂的愈创木酚收率最高 ,在反应温度为 5 5 3K时 ,邻苯二酚转化率和愈创木酚收率分别为 92 %和 86%

涡旋辅助液液微萃取结合GC-MS法检测67种白酒中四甲基吡嗪、4-甲基愈创木酚和4-乙基愈创木酚

采用涡旋辅助液液微萃取结合气相色谱-质谱(gas chromatography-mass spectrometry,GC-MS)法对67种白酒中四甲基吡嗪、4-甲基愈创木酚和4-乙基愈创木酚进行检测。酒样经二氯甲烷提取,涡旋辅助萃取1 min,6 000 r/min离心5 min,然后采用GC-MS进行分析。结果表明,四甲基吡嗪、4-甲基愈创木酚和4-乙基愈创木酚分别在质量浓度为0.5~2 500、1.0~2 500、1.0~2 500μg/L的范围内具有较好的线性关系(R2>0.99);检出限分别为0.25、0.5、0.5μg/L;不同添加水平的平均回收率为80.1%~88.0%。对67种白酒含量分析表明,所有样本都含有四甲基吡嗪,含量范围为1.5~2 434.3μg/L;51种样本中含有4-甲基愈创木酚,含量范围为2.8~1 709.0μg/L;53种样本中含有4-乙基愈创木酚,含量范围为1.3~1 167.5μg/L。白酒酿造原料、工艺的差异可能是造成其健康因子含量不同的潜在因素。

Ni/SiO_2-ZrO_2催化剂焙烧温度对其催化愈创木酚加氢脱氧性能的影响(英文)

采用化学沉淀法合成了SiO2-ZrO2复合氧化物载体,并以浸渍法制备了Ni/SiO2-ZrO2双功能催化剂,考察了焙烧温度对催化剂结构及其催化愈创木酚加氢脱氧制环己烷性能的影响.结果表明,经500°C焙烧催化剂的加氢脱氧活性最高,在Ni金属中心和SiO2-ZrO2载体材料的协同作用下,愈创木酚转化率为100%,环己烷选择性为96.8%.对催化剂进行N2物理吸附、H2化学吸附、X射线衍射分析、H2程序升温还原、NH3程序升温脱附与Raman光谱等表征后发现,合成的SiO2-ZrO2为无定形的酸碱两性氧化物;经500°C焙烧的催化剂样品的有效比表面积和孔体积均明显增大,表面酸量最多,硝酸镍分解成小颗粒的NiO较易被H2还原,这些特性是该催化剂样品具有高效加氢脱氧活性的原因.