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.

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.

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.

“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.

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 kg-1).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 kg-1) 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.

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.

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.

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.

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.

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。

浓香型白酒发酵过程中4-甲/乙基愈创木酚的代谢规律分析

4-甲/乙基愈创木酚是浓香型白酒中重要的风味和健康成分,是影响白酒烟熏、丁香风味及抗氧化、抗炎等健康特性的重要因素,但其在浓香型白酒发酵过程中的代谢规律不清晰。因此,该文首先采用真空辅助吸附萃取分析法(vacuum assisted adsorption extraction,VASE)结合GC-MS分析揭示浓香型白酒发酵过程中4-甲/乙基愈创木酚及其前体物质的变化规律。研究发现:(1)4-甲/乙基愈创木酚的前体物质(阿魏酸、4-乙烯基愈创木酚)是由原料提供的,其中对阿魏酸的贡献粮食约为65.13%、大曲20.69%、稻壳14.18%;对于4-乙烯基愈创木酚的贡献稻壳最大,约为98.29%、大曲0.28%、粮食1.33%;(2)发酵过程中,4-甲/乙基愈创木酚主要在窖池发酵阶段产生,尤其是于窖池发酵后期产生,4-甲基愈创木酚由53.63μg/kg增长到93.78μg/kg,生成率达74.86%,4-乙基愈创木酚的含量由13.14μg/kg达到53.98μg/kg,生成率超过300%。该研究系统揭示了浓香型白酒发酵过程中4-甲/乙基愈创木酚及其前体物质的变化规律,为调控4-甲/乙基愈创木酚代谢提高浓香型白酒风味健康品质具有重要意义。

产4-乙基愈创木酚菌株的筛选、鉴定及其在酱油酿造中的应用

该研究采用传统培养分离方法结合耐盐性及4-乙基愈创木酚(4-EG)生产能力测定,从广式高盐稀态酱油发酵酱醪中分离筛选能转化阿魏酸(FA)生成4-EG的细菌,通过形态观察及分子生物学技术对分离菌株进行鉴定,同时对其生长特性进行研究,并将其应用于酱油酿造。结果表明,分离筛选得到一株高产4-EG的菌株JLB30-2,被鉴定为枯草芽孢杆菌(Bacillus subtilis),该菌株在45℃、160 r/min、20%盐含量环境下,能将发酵液中的FA转化为4-EG。菌株JLB30-2在盐含量为20%的酱醪中培养60 d,4-EG含量最高达29.75 mg/L,是对照组(6.85 mg/L)的3.34倍,同时增加了酱油中氨基酸、酮类化合物的含量,强化了酱油醇香和酱香,提高了酱油的感官品质,对改善提升酱油品质具有重要实用价值。

广式酿造酱油生产条件的优化

本文以广式高盐稀态酿造酱油为基础,通过对比不同发酵周期下原油中风味物质的变化,结合5’-呈味核苷酸二钠、蔗糖素的使用,综合提升酱油产品的感官品质。结果表明,随着发酵周期的增长,原油中风味物质的含量不断提高,但当发酵周期大于115 d,原油中还原糖含量开始下降。从原油指标需求以及生产周期综合评定后确认发酵周期115 d为宜(可随季节上下波动10~15 d)。该条件下辅以I+G添加量为1.3‰,蔗糖素添加量为0.10‰时,酱油产品感官最佳。

聚苯乙烯/Fe_(3)O_(4)悬浮填料的制备及类芬顿处理愈创木酚模拟废水的研究

均相芬顿(Fenton)处理废水存在化学药剂投加量大、铁泥产生量多的问题,类Fenton是有效的解决途径之一。本课题以羟基修饰的纳米Fe_(3)O_(4)(Fe_(3)O_(4)-OH)和苯乙烯(St)为主要原料,利用链式加聚反应合成聚苯乙烯(PS)/Fe_(3)O_(4)悬浮填料,用于类Fenton处理愈创木酚模拟废水。分别用傅里叶变换红外光谱仪(FT-IR)、热重分析仪(TGA)、超景深显微镜、扫描电子显微镜(SEM)、X射线能谱仪(EDS)对PS/Fe_(3)O_(4)悬浮填料进行分析和表征,发现PS/Fe_(3)O_(4)悬浮填料具有Fe_(3)O_(4)-OH和PS的双层复合结构,其中Fe_(3)O_(4)的质量占比为51.6%。对比研究了PS/Fe_(3)O_(4)悬浮填料和纳米Fe_(3)O_(4)类Fenton降解愈创木酚的效果,发现PS/Fe_(3)O_(4)悬浮填料的处理效果更优,在最佳工艺条件:初始pH值为4,m(CODCr)∶m(H_(2)O_(2))=1∶1.5,悬浮填料投加量为0.8 g/L,反应时间为120 min下,愈创木酚降解率达到88.63%。通过自由基猝灭实验证明Fe_(3)O_(4)修饰前后愈创木酚的类Fenton降解体系的主要活性自由基仍为·OH。

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。