Design of Multiple Metal Doped Ni Based Catalyst for Hydrogen Generation from Bio-oil Reforming at Mild-temperature

A new kind of multiple metal (Cu, Mg, Ce) doped Ni based mixed oxide catalyst, synthesized by the co-precipitation method, was used for efficient production of hydrogen from bio-oil reforming at 250-500 oC. Two reforming processes, the conventional steam reforming (CSR) and the electrochemical catalytic reforming (ECR), were performed for the bio-oil reforming. The catalyst with an atomic mole ratio of Ni:Cu:Mg:Ce:Al=5.6:1.1:1.9:1.0:9.9 exhibited very high reforming activity both in CSR and ECR processes, reaching 82.8% hydrogen yield at 500 oC in the CSR, yield of 91.1% at 400 oC and 3.1 A in the ECR, respectively. The influences of reforming temperature and the current through the catalyst in the ECR were investigated. It was observed that the reforming and decomposition of the bio-oil were significantly enhanced by the current. The promoting effects of current on the decomposition and reforming processes of bio-oil were further studied by using the model compounds of bio-oil (acetic acid and ethanol) under 101 kPa or low pressure (0.1 Pa) through the time of flight analysis. The catalyst also shows high water gas shift activity in the range of 300-600 oC. The catalyst features and alterations in the bio-oil reforming were characterized by the ICP, XRD, XPS and BET measurements. The mechanism of bio-oil reforming was discussed based on the study of the elemental reactions and catalyst characterizations. The research catalyst, potentially, may be a practical catalyst for high efficient production of hydrogen from reforming of bio-oil at mild-temperature.     

Production of Hydrogen from Bio-oil Using Low-temperature Electrochemical Catalytic Reforming Approach over CoZnAl Catalyst

High-efficient production of hydrogen from bio-oil was performed by electrochemical catalytic reforming method over the CoZnAl catalyst. The influence of current on the hydrogen yield, carbon conversion, and products distribution were investigated. Both the hydrogen yield and carbon conversion were remarkably enhanced by the current through the catalyst, reaching hydrogen yield of 70% and carbon conversion of 85% at a lower reforming temperature of 500 oC. The influence of current on the properties of the CoZnAl catalyst was also characterized by X-ray diffraction, X-ray photoelectron spectroscopy, thermal gravimetric analysis, and Brunauer-Emmett-Teller measurements. The thermal electrons would play an important role in promoting the reforming reactions of the oxygenated-organic compounds in the bio-oil.     

在Ni/HZSM-5催化剂上低温水蒸汽重整生物油制氢

We investigated high catalytic activity of Ni/HZSM-5 catalysts synthesized by the impregna-tion method, which was successfully applied for low-temperature steam reforming of bio-oil. The influences of the catalyst composition, reforming temperature and the molar ratio of steam to carbon fed on the stream reforming process of bio-oil over the Ni/HZSM-5 catalysts were investigated in the reforming reactor. The promoting effects of current passing through the catalyst on the bio-oil reforming were also studied using the electrochemical catalytic re-forming approach. By comparing Ni/HZSM-5 with commonly used Ni/Al₂O₃ catalysts, the Ni₂₀/ZSM catalyst with Ni-loading content of about 20% on the HZSM-5 support showed the highest catalytic activity. Even at 450 oC, the hydrogen yield of about 90% with a near complete conversion of bio-oil was obtained using the Ni₂₀/ZSM catalyst. It was found that the performance of the bio-oil reforming was remarkably enhanced by the HZSM-5 supporter and the current through the catalyst. The features of the Ni/HZSM-5 catalysts were also investigated via X-ray diffraction, inductively coupled plasma and atomic emission spectroscopy, hydrogen temperature-programmed reduction, and Brunauer-Emmett-Teller methods.     

Effects of Current upon Electrochemical Catalytic Reforming of Anisole

The reforming of anisole (as model compound of bio-oil) was performed over the NiCuZn-Al₂O₃ catalyst, using a recently-developed electrochemical catalytic reforming (ECR). The influence of the current on the anisole reforming in the ECR process has been investigated. It was observed that anisole reforming was significantly enhanced by the current approached over the catalyst in the electrochemical catalytic process, which was due to the non-uniform temperature distribution in the catalytic bed and the role of the thermal electrons orig-inating from the electrified wire. The maximum hydrogen yield of 88.7% with a carbon conversion of 98.3% was obtained through the ECR reforming of anisole at 700 oC and 4 A. X-ray diffraction was employed to characterize catalyst features and their alterations in the anisole reforming. The apparent activation energy for the anisole reforming is calculated as 99.54 kJ/mol, which is higher than ethanol, acetic acid, and light fraction of bio-oil. It should owe to different physical and chemical properties and reforming mechanism for different hydrocarbons.     

一种适用于生物油低温制氢的碳纳米纤维促进的镍催化剂

氢气作为一种高热值的清洁能源广泛地应用于工业中. 研究证明: 生物质通过化学过程可以转化为多种气体燃料(氢气), 液体燃料以及高附加值的化学品. 生物质作为一种环境友好型再生洁净能源, 其研究越来越受到关注. 本文旨在探讨利用生物油为原料, 通过水蒸汽重整方法制备富氢合成气的过程. 利用均匀浸渍的方法制备了一种高分散的碳纳米纤维促进的镍(Ni/CNFs)催化剂, 并将普通的Al₂O₃作为载体的Ni/Al₂O₃催化剂和Ni/CNFs作对比. 研究了重整温度以及水蒸汽和碳摩尔比(n_S/n_C)对生物油水蒸汽重整制氢的影响. 结果表明: 碳纳米纤维作为载体用于生物油水蒸汽重整制氢的效果要远优于普通的Al₂O₃载体, 利用22% Ni/CNFs 催化剂时, 在实验温度范围内(350-550℃), 最高生物油转化率和氢气产率分别达到了94.7%和92.1%, 通过研究重整条件以及对催化剂进行表征探讨了生物油在水蒸汽重整过程中催化剂的构效关系.     

C12A7-Mg催化剂水蒸汽重整生物油、石脑油和CH4制氢

Hydrogen production by catalytic steam reforming of the bio-oil, naphtha, and CH4 was investigated over anovel metal-doped catalyst of (Ca24Al28O64)4+￠4O-/Mg (C12A7-Mg). The catalytic steam reforming wasinvestigated from 250 to 850 ±C in the ˉxed-bed continuous °ow reactor. For the reforming of bio-oil, theyield of hydrogen of 80% was obtained at 750 ±C, and the maximum carbon conversion is nearly close to95% under the optimum steam reforming condition. For the reforming of naphtha and CH4, the hydrogenyield and carbon conversion are lower than that of bio-oil at the same temperature. The characteristics ofcatalyst were also investigated by XPS. The catalyst deactivation was mainly caused by the deposition ofcarbon in the catalytic steam reforming process.     

Electrochemical catalytic reforming of oxygenated-organic compounds: a highly efficient method for production of hydrogen from bio-oil

A novel approach to produce hydrogen from bio-oil was obtained with high carbon conversion (>90%) and hydrogen yield (>90%) at T<500 degrees C by using the electrochemical catalytic reforming of oxygenated-organic compounds over 18%NiO/Al(2)O(3) reforming catalyst; thermal electrons play important promoting roles in the decomposition and reforming of the oxygenated-organic compounds in the bio-oil.     

Production of Bio-hydrogen Using Bio-oil as a Potential Biomass-derived Renewable Feedstock

The bio-oil derived from pyrolysis of straw can be selectively converted into high-purity hydrogen by coupling three steps:(i)steam refonning(SR)of di tierent bio-oils,(ii)water-gas shift(WGS),and(iii)the removal of CO2.the catalytic SR reaction over the NiLaTiAl catalyst,coupled with a low-temperature WGS reaction with the CuZnAl catalyst,promoted the conversion of various oxygen-contaming organic compounds in the bio-oil into hydrogen and carbon dioxide.Under the optimized condition,light bio-oil achieved the highest conversion(99.8%,molar fraction),with a high hydrogen yield of 16.4%(mass traction)and a H2 purity of 99.94%(volume fraction).The carbon deposition on the NiLaTiAl catalyst was the main factor caused catalyst deactivation.Production of hydrogen from different bio-oil model compounds was also investigated in detail.     

Effects of Preparation Method on the Performance of Ni/Al2O3 Catalysts for Hydrogen Production by Bio-Oil Steam Reforming

Steam reforming of bio-oil derived from the fast pyrolysis of biomass is an economic and renewable process for hydrogen production. The main objective of the present work has been to investigate the effects of the preparation method of Ni/Al₂O₃ catalysts on their performance in hydrogen production by bio-oil steam reforming. The Ni/Al₂O₃ catalysts were prepared by impregnation, co-precipitation, and sol?Cgel methods. XRD, XPS, H₂-TPR, SEM, TEM, TG, and N₂ physisorption measurements were performed to characterize the texture and structure of the catalysts obtained after calcination and after their subsequent use. Ethanol and bio-oil model compound were selected for steam reforming to evaluate the catalyst performance. The catalyst prepared by the co-precipitation method was found to display better performance than the other two. Under the optimized reaction conditions, an ethanol conversion of 99% and a H₂ yield of 88% were obtained.     

Maximum Hydrogen Production by Autothermal Steam Reforming of Bio-oil With NiCuZnAl Catalyst

Autothermal steam reforming (ATR) of bio-oil, which couples the endothermic steam reform-ing reaction with the exothermic partial oxidation, offers many advantages from a technical and economic point of view. Effective production of hydrogen through ATR of bio-oil was performed at lower temperature with NiCuZnAl catalyst. The highest hydrogen yield from bio-oil reached 64.3% with a nearly complete bio-oil conversion at 600 oC, the ratio of steam to carbon fed (S/C) of 3 and the oxygen to carbon ratio (O/C) of 0.34. The reaction con-ditions in ATR including temperature, O/C, S/C and weight hourly space velocity can be used to control both hydrogen yield and products distribution. The comparison between the ATR and common steam reforming of bio-oil was studied. The mechanism of the ATR of bio-oil was also discussed.     

HZSM-5在线提质生物油及催化剂失活机理分析

对不同使用时间的HZSM-5分子筛在线催化提质制取的生物油进行理化特性和成分分析,从生物油品质角度对HZSM-5的催化性能进行评价;并采用TG、BET、XRD、SEM和TEM等方法对失活的HZSM-5催化剂进行表征分析,探讨了HZSM-5催化提质生物油的失活机理,并进行再生研究。研究表明,HZSM-5分子筛可转化生物油中的酸类、醛类和酮类等"非期望"有机物,生成较多"期望"有机物,如酚类和芳烃类物质,降低生物油的氧含量及酸性,提高生物油的热值;HZSM-5使用80 min后,生物油品质明显变差,催化剂活性明显降低;失活催化剂上沉积的焦炭主要呈纤维状,同时,还存在少量石墨状焦炭,焦炭总量达14.12%,且使用过程中催化剂的比表面积和孔容均下降,晶粒的团聚现象加剧,结晶度下降;在催化提质过程中,在孔道内生成的石墨状焦炭及在表面形成的纤维状焦炭大量覆盖活性位点,使得催化剂失活。经550℃再生后,催化剂可恢复催化性能。     

餐饮垃圾热解制取生物燃油的实验研究

主要研究温度、餐饮垃圾种类以及催化剂对餐饮垃圾热解所制生物燃油的产率和品质的影响。结果表明,猪肉和米饭的最佳产油温度均为410℃,白菜的最佳产油温度为450℃。米饭、白菜、猪肉的产油率分别为45.02%、25.60%、71.26%。采用氧弹热量计对其热值进行测定,米饭和白菜热解油的高位热值较低,分别为18.30MJ/kg和17.49MJ/kg;而猪肉热解油的高位热值为36.57 MJ/kg, 并且黏稠度较高。催化剂Co-MCM-41的催化效果明显,使餐饮垃圾的产油率由41.99%提高到66.30%,同时使热解油中的含氧化合物明显降低,而烷烃类和烯烃类的含量明显增加,高位热值由30.30MJ/kg提高到32.74MJ/kg。通过物理吸附仪对新制备的和使用一次后再生的催化剂Co-MCM-41进行表征,结果表明,催化剂Co-MCM-41再生后孔容、孔径和比表面积变化不大,性质基本不变,活性依然存在。
     

C12A7-MgO催化剂上的生物油裂解制氢

Catalytic steam reforming of condensable vapors, i.e. bio-oil, derived from pyrolysis of biomass is an important process for hydrogen production, which is expected to form renewable and clean energy. The generation of hydrogen from bio-oil was investigated from 250 to 750 ℃ by a MgO mixed C12A7-O-(C12A7-MgO) catalyst in a fixed-bed micro-reactor. The hydrogen yield on C12A7-MgO was about 44% at 750 ℃. It is found that both the catalytic activity and catalysis life are improved by doping MgO. The XRD results show that the C12A7 structure of the positively charged lattice framework remains in the C12A7-MgO catalyst.     

Ni/Al2O3改性催化剂催化重整生物油模拟物制氢研究

制备了Ni/Al₂O₃、Ni-Cu/Al₂O₃、Ni-Co/Al₂O₃和Ni-Co-Cu/Al₂O₃催化剂,研究了Co和Cu对生物油水蒸气催化重整的影响。实验表明,Co 能促进水汽变换(WGS)反应,提高氢气的产率,Cu能抑制反应中焦炭的形成,提高催化剂的稳定性。对催化剂Ni-Co-Cu/Al₂O₃进行工艺条件考察,当900 ℃、水油比为6 g/g、质量空速(WHSV)为1 h^-1时,碳选择性达到87.5%,氢气产率达到84.2%,潜在氢气产率达到92.4%。     

Transformation of Bio-oil into BTX by Bio-oil Catalytic Cracking

Production of benzene, toluene and xylenes (BTX) from bio-oil can provide basic feedstocks for the petrochemical industry. Catalytic conversion of bio-oil into BTX was performed by using different pore characteristics zeolites (HZSM-5, HY-zeolite, and MCM-41). Based on the yield and selectivity of BTX, the production of aromatics decreases in the following order: HZSM-5>MCM-41>HY-zeolite. The highest BTX yield from bio-oil using HZSM-5 reached 33.1% with aromatics selectivity of 86.4%. The reaction conditions and catalystcharacterization were investigated in detail to make clear the optimal operating parameters and the relation between the catalyst structure and the production of BTX.     

Aromatics and phenols from catalytic pyrolysis of Douglas fir pellets in microwave with ZSM-5 as a catalyst

Microwave assisted catalytic pyrolysis was investigated to convert Douglas fir pellets to bio-oils by a ZSM-5 zeolite catalyst. A central composite experimental design (CCD) was used to optimize the catalytic pyrolysis process. The effects of reaction time, temperature and catalyst to biomass ratio on the bio-oil, syngas, and biochar yields were determined. GC/MS analysis results showed that the bio-oil contained a series of important and useful chemical compounds. Phenols, guaiacols, and aromatic hydrocarbons were the most abundant compounds which were about 50–82% in bio-oil depending on the pyrolysis conditions. Comparison between the bio-oils from microwave pyrolysis with and without catalyst showed that the catalyst increased the content of aromatic hydrocarbons and phenols. A reaction pathway was proposed for microwave assisted catalyst pyrolysis of Douglas fir pellets.     

助剂对泡沫金属微反应器内二甲醚水蒸气重整制氢的影响

采用共沉淀耦合机械混合法制备了CuO-ZnO-Al₂O₃/HZSM-5双功能催化剂用于二甲醚水蒸气重整制氢的研究,结合BET、H₂-TPR、XRD、SEM等表征手段,在泡沫金属微反应器内考察助剂Cr、Zr、Ce、Co对双功能催化剂催化性能的影响。研究结果表明,加入Cr助剂后, 可以有效降低催化剂的平均孔径和还原温度,并抑制催化剂制备过程中氢氧化锌晶相的形成,催化剂的低温催化性能明显提高,二甲醚的转化率和氢收率在较低温度下即可分别达到99%和95%,表现出了良好的低温反应活性。考察了反应温度、空速和水醚比等条件对二甲醚水蒸气重整催化剂催化活性的影响,在250℃、空速3 884 mL/(g·h)、水醚比为5的条件下,CuO-ZnO-Al₂O₃-Cr₂O₃/ HZSM-5催化二甲醚水蒸气重整反应进行50 h,二甲醚的转化率维持在97%以上,催化剂的活性没有明显下降。     

生物油水溶性组分的水蒸气催化重整制氢实验研究

利用固定床反应器对生物油水溶性组分重整制氢反应进行了考察,研究了温度、吸收剂的加入对反应过程的影响。结果表明,在常压条件下生物油水溶性组分的最佳重整温度为800℃,此时H2体积分数为60%、CO体积分数为10%。加入CO₂吸收剂后,H₂体积分数提高了25%,H₂产率提高了10%。在常压条件下,以CaO作为吸收剂时,最佳的反应温度为600℃,此时H₂体积分数最高可达85%。650℃时CaO对CO₂的吸收能力减弱导致其对生成H₂反应的促进作用急剧降低。     

CeO_2对Ni-Cu/HZSM-5催化剂在生物油加氢脱氧反应中抗积炭性能的影响

将CeO_2氧化物添加到Ni-Cu基催化剂中,研究了CeO_2加入量对生物油加氢脱氧过程中催化剂表面积炭行为的影响。采用热重分析、X射线光电子能谱和拉曼光谱等对CeO_2加入前后催化剂表面的积炭量、微结构、积炭动力学和不同类型炭(软积炭、硬积炭和石墨炭)的转变行为等进行了研究。结果表明,CeO_2的添加量及反应温度对催化剂的抗积炭能力及积炭的类型均具有显著的影响;在反应温度为270℃、CeO_2的添加量为15%时,Ni-Cu基催化剂抗积炭性能最好。     

生物质炭和富二氧化碳合成气制取二甲醚

研究了一种利用富二氧化碳合成气和生物质炭联合制取二甲醚的方法, 其过程包括两个步骤: 富二氧化碳合成气调整以及调整后合成气合成二甲醚. 在合成气调整过程中, 利用生物质炭为原料在Ni/Al₂O₃催化剂上将富二氧化碳合成气调整为富一氧化碳合成气. 经过800 °C合成气调整后, 合成气中CO₂含量大幅降低而CO含量大幅提高, CO₂/CO的摩尔比从原始合成气的6.33降至0.21. 然后, 分别用调整前后的合成气合成二甲醚, 结果表明, 经过调整后, C转化率得到很大的提高, 二甲醚产率比调整前高4倍. 本工作提供了一种可利用富二氧化碳生物质合成气制取燃料的途径, 并且提供了一种新的利用生物质炭的方法.