二硒化钴电催化剂的制备及氧还原性能测试

具有高附加值的绿色环保型氧化剂——过氧化氢(H₂O₂)的需求日益增加，急需发展绿色且安全的H₂O₂合成新方法。两电子氧还原反应(2e^-ORR)是一种制备H₂O₂的高效方法，其中催化剂的高效率和高选择性是2e^-ORR的关键。对二硒化钴(CoSe₂)电催化剂的制备和性能测试实验进行了探索。首先，通过联氨还原法制备钴纳米粒子；然后，通过简单的固相反应并在不同温度下退火制备CoSe₂电催化剂；最后，通过一系列的表征方法对CoSe₂电催化剂的表面形貌、晶型、电化学及其稳定性等进行了研究。为2e^-ORR电催化剂CoSe₂的进一步研究和应用开发提供借鉴。     

Ni-Mn/Al2O3催化剂在浆态床中CO甲烷化催化性能

采用共浸渍法制备了Ni-Mn/Al₂O₃催化剂,考察了助剂Mn的含量对催化剂结构及浆态床CO甲烷化性能的影响。采用XRD、H₂-TPR、BET、TEM、H₂-化学吸附等表征对催化剂进行了测试分析,结果表明,Mn助剂的引入能够促进Ni物种在载体表面的分散,减弱Ni物种与载体的相互作用,降低催化剂的还原温度,提高催化剂的比表面积,减小活性金属Ni的晶粒尺寸。随着Mn含量的增加,Ni-Mn/Al₂O₃催化剂的甲烷化性能先升后降,其中以Mn含量为4%（质量分数）时的催化甲烷化性能最佳,添加过量的Mn导致活性组分Ni被部分覆盖,催化甲烷化性能下降。通过对16Ni4Mn/Al₂O₃催化剂样品的浆态床反应温度及反应压力的研究发现,当反应温度为280℃、反应压力为1.5 MPa时,催化剂样品16Ni4Mn/Al₂O₃的CO转化率及CH₄选择性分别达到96.2%和88.8%。     

载体焙烧温度对Ni/SiO2-Al2O3催化剂稳定性的影响

为了获得高水热稳定的负载Ni催化剂,延长催化剂在含水液相体系中的使用寿命,以不同温度焙烧的SiO₂-Al₂O₃为载体,采用浸渍法制备Ni/SiO₂-Al₂O₃催化剂,通过吡啶-原位傅立叶变换红外光谱、X射线衍射、NH₃-程序升温脱附和H₂-程序升温还原等方法进行表征,以水相1,4-丁炔二醇加氢为探针反应,研究载体焙烧温度对Ni/SiO₂-Al₂O₃催化剂催化加氢性能及含水体系中稳定性的影响。结果表明,在(400~800) ℃,随着载体焙烧温度升高,活性组分Ni存在状态及催化剂加氢活性变化较小,但催化剂的水热稳定性下降,造成这一现象的原因是随着载体焙烧温度升高,载体表面SiO₂聚集,暴露的Al³⁺增加,载体水合程度增大。载体焙烧温度400 ℃时,Ni/SiO₂-Al₂O₃催化剂表现出最佳的水热稳定性。     

镍源对Ni/Al2O3结构及其1,4-丁炔二醇加氢催化性能构效关系的影响

本文通过溶液燃烧法,分别以Ni(CH₃COO)₂·4H₂O、Ni(NO₃)₂·6H₂O、NiCl₂·6H₂O和NiSO₄·6H₂O为镍源制备系列Ni/Al₂O₃催化剂,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附、程序升温还原(H₂-TPR)等表征手段,进一步揭示了镍源对合成Ni/Al₂O₃催化剂结构与其催化加氢性能间的构效关系的影响,结果表明,以Ni(CH₃COO)₂·4H₂O为镍源制备的Ni/Al₂O₃催化剂比表面积最大,达到225m²·g^-1,最大孔容0.39c...     

载体对镍基催化剂顺酐液相加氢性能的影响

分别以ZrO₂、SiO₂与Al₂O₃为载体,采用等体积浸渍法制备了Ni质量分数为15%的催化剂,考察了其催化顺酐液相加氢性能,并利用BET、XRD、H₂-TPR以及TPO-MS等表征手段对催化剂进行了详细表征。结果表明,随载体不同各催化剂的加氢活性及选择性存在较大差异,Ni/Al₂O₃催化剂的C=C键加氢活性最高,但其几乎没有C=O加氢活性,催化顺酐加氢主产物为丁二酸酐。Ni/ZrO₂催化剂具有最高的C=O加氢活性,催化顺酐加氢主产物为γ-丁内酯,在反应温度为483 K,氢气压力为5 MPa的条件下反应8 h时,Ni/ZrO₂催化剂的γ-丁内酯选择性达79.20%。催化剂的套用实验表明,Ni/ZrO₂与Ni/SiO₂催化剂具有高的使用稳定性,Ni/Al₂O₃催化剂则在套用过程中快速失活。顺酐加氢至γ-丁内酯的中间产物--丁二酸酐与催化剂间的相互作用是影响催化剂加氢选择性及使用稳定性的主要原因。     

甘油水蒸汽重整制氢Ni/Ce0.9Gd0.1O1.95催化剂的研究

采用浸渍法和共沉淀法制备了Ni质量分数10%的10%Ni/Ce_0.9Gd_0.1O_1.95催化剂,通过X射线衍射、N₂物理吸附与H₂脉冲化学吸附、H₂程序升温还原等技术表征了催化剂的结构和性质,并考察了其催化甘油水蒸汽重整制氢反应性能。结果表明,浸渍法制备的10%Ni/Ce_0.9Gd_0.1O_1.95-S催化剂的活性最佳,该催化剂上Ni晶粒小、分散度高,形成氧空穴使得催化剂抗积炭能力大大提高,所以活性、氢气选择性较高,稳定性也较好。同时考察了水与甘油物质的量比和泵流速对甘油重整反应性能的影响,发现在水与甘油物质的量比为24:1,泵流速为0.06 mL·min^-1的条件下,甘油几乎完全转化,氢气选择性也非常高,而且反应10 h没有失活。     

CeO2改性Ni/γ-Al2O3催化剂上顺酐加氢制备丁二酸酐

采用等体积浸渍法制备CeO₂改性Ni/γ-Al₂O₃催化剂,通过BET、XRD、H₂-TPR和SEM等对催化剂结构及物化性能进行表征,考察Ni-CeO₂/γ-Al₂O₃催化剂对顺酐催化加氢制备丁二酸酐催化性能的影响。结果表明,引入适量CeO₂可提高催化剂活性组分Ni的分散度,增加催化剂比表面积,提高催化剂热稳定性。采用负载CeO₂质量分数5%的Ni-CeO₂/γ-Al₂O₃催化剂,在反应温度120 ℃、反应压力2.0 MPa和空速0.6 h^-1条件下,顺酐转化率为99.5%,丁二酸酐选择性为99.4%。     

整体式Ni-Co双金属催化剂生物质燃气提质性能

以蜂窝陶瓷为载体,使用浸渍法负载Ni、Co双金属,形成整体式催化剂,研究其催化生物质燃气合成低碳烃性能,并采用N₂等温吸附、H₂-TPR等对催化剂进行表征。结果表明,在360℃、H₂/CO=2和0.3 MPa的反应条件下,Ni、Co负载量分别为2%和4%时,催化剂具有最优催化性能,CO转化率可达93.60%,产气低位热值为9.84 MJ/Nm³,较进气提高了26.82%。与Ni单金属催化剂相比,添加Co可在降低CH₄和CO₂选择性的同时,提高C₂-C₃的选择性,从而有利于提高燃气热值;Co的引入虽有助于增强催化剂的抗烧结能力,但积碳量却有所上升。     

稻壳白炭黑负载Fe2O3的气相芬顿反应NO预氧化

以稻壳为硅源,采用直接煅烧法制备白炭黑,以其为载体,采用共浸渍法制备Fe₂O₃/SiO₂催化剂;并采用同样方法以商用二氧化硅为载体制备Fe₂O₃/C-SiO₂催化剂,将二者用于催化H₂O₂预氧化NO的实验。探究不同工况（负载量、催化温度、H₂O₂汽化温度、H₂O₂流量和水汽浓度）对NO预氧化的影响,并对催化剂进行表征,分析其物理化学性质对催化性能的影响。结果表明,在负载量为50%、催化温度为140℃、H₂O₂汽化温度为120℃、H₂O₂流量为2.5mL/h时,达到最佳工况,NO氧化度能达到73%;在相同实验条件下Fe₂O₃/SiO₂催化剂的预氧化效果要比Fe₂O₃/C-SiO₂催化剂高20%左右。TPR结果表明载体可以降低活性组分的还原温度,减少活性组分的团聚;催化剂的晶相结构稳定,机械强度及热稳定性良好;ESR和XPS结果显示Fe₂O₃/SiO₂催化剂的催化性能优于Fe₂O₃/C-SiO₂催化剂,能够更好地催化分解H₂O₂产生·OH。     

NaOH改性MnO2/γ-Al2O3催化尿素醇解合成碳酸丙烯酯

采用超声浸渍法制备了MnO₂/γ-Al₂O₃催化剂,并用碱和盐对其进行了改性.采用X射线衍射仪(XRD)、CO₂-TPD对改性后的MnO₂/γ-Al₂O₃催化剂进行了表征,研究了改性后催化剂在尿素醇解合成碳酸丙烯酯(PC)反应中的催化性能.研究结果表明,NaOH改性MnO₂/γ-Al₂O₃催化剂具有最好的催化性能;同时催化剂的焙烧时间、焙烧温度以及NaOH改性量影响催化剂表面碱性活性中心的数量和强度,其中中强碱的增加是改性后催化剂活性提高的主要原因.在NaOH用量为MnO₂质量的10%,400℃焙烧2h后,改性MnO₂/γ-Al₂O₃催化剂表面的中强碱量最大,催化活性最高,PC收率与选择性分别达86.9%、91.8%.     

An efficient bifunctional Ni-Nb2O5 nanocatalysts for the hydrodeoxygenation of anisole

The Ni-Nb₂O₅ nanocatalysts have been prepared by the sol–gel method, and the catalytic hydrodeoxygenation (HDO) performance of anisole as model compound is studied. The results show that Nb exists as amorphous Nb₂O₅ species, which can promote Ni dispersion. The addition of Nb₂O₅ increases the acidity of the catalyst. However, when the content of niobium is high, there is an inactive Nb-Ni-O mixed phase. The size and morphology of Ni grains in catalysts are different due to the difference of Nb/Ni molar ratio. The Ni_0.9Nb_0.1 sample has the largest surface area of 170.8 m²·g^-1 among the catalysts prepared in different Nb/Ni molar ratios, which is mainly composed of spherical nanoparticles and crack pores. The HDO of anisole follows the reaction route of the hydrogenation HYD route. The Ni_0.9Nb_0.1 catalyst displayed a higher HDO performance for anisole than Ni catalyst. The selectivity to cyclohexane over the Ni_0.9Nb_0.1 sample is about 10 times that of Ni catalyst at 220 ℃ and 3 MPa H₂. The selectivity of cyclohexane is increased with the increase of reaction temperature. The anisole is almost completely transformed into cyclohexane at 240 ℃, 3 MPa H₂ and 4 h.     

Catalytic synthesis of methanethiol from hydrogen sulfide and carbon monoxide over vanadium-based catalysts

The direct synthesis of methanethiol, CH₃SH, from CO and H₂S was investigated using sulfided vanadium catalysts based on TiO₂ and Al₂O₃. These catalysts yield high activity and selectivity to methanethiol at an optimized temperature of 615 K. Carbonyl sulfide and hydrogen are predominant products below 615 K, whereas above this temperature methane becomes the preferred product. Methanethiol is formed by hydrogenation of COS, via surface thioformic acid and methylthiolate intermediates. Water produced in this reaction step is rapidly converted into CO₂ and H₂S by COS hydrolysis.

Titania was found to be a good catalyst for methanethiol formation. The effect of vanadium addition was to increase CO and H₂S conversion at the expense of methanethiol selectivity. High activities and selectivities to methanethiol were obtained using a sulfided vanadium catalyst supported on Al₂O₃. The TiO₂, V₂O₅/TiO₂ and V₂O₅/Al₂O₃ catalysts have been characterized by temperature programmed sulfidation (TPS). TPS profiles suggest a role of V₂O₅ in the sulfur exchange reactions taking place in the reaction network of H₂S and CO.     

Production of hydrogen for fuel cells by reformation of biomass-derived ethanol

The reformation of biomass-derived ethanol to a hydrogen-rich gas stream suitable for feeding fuel cells is investigated as an efficient and environmentally friendly process for the production of electricity for mobile and stationary applications. Steam reforming of ethanol is investigated over Ni catalysts supported on La₂O₃, Al₂O₃, YSZ and MgO. The influence of several parameters on the catalytic activity and selectivity is examined including reaction temperature, water-to-ethanol ratio and space velocity. Results reveal that the Ni/La₂O₃ catalyst exhibits high activity and selectivity toward hydrogen production and, most important, long term stability for steam reforming of ethanol. The enhanced stability of this catalyst may be due to scavenging of coke deposition on the Ni surface by lanthanum oxycarbonate species which exist on top of the Ni particles under reaction conditions.     

Preparation and characterization of neodymium hydroxide powder via the hydration method

The preparation of Nd(OH)₃ powder by the direct hydration method using Nd₂O₃ as a raw material was studied, and the effects of stirring mode, H₂O and Nd₂O₃ molar ratio, stirring rate, and reaction time on temperature change and conversion rate in a hydration system were analyzed. The reasonable process conditions for the direct hydration of Nd(OH)₃ by Nd₂O₃ were then determined. Process, morphology, and structure were considered in the preparation of neodymium hydroxide powder, and its composition was investigated by X-ray powder diffraction, scanning electron microscopy, laser particle size analysis, thermogravimetric differential thermal analysis, and chemical analysis. It has been proved that the process is simple and feasible, in line with the concept of modern green chemistry, and the products also meet the market requirements.     

Pt/TiO_2催化二甲醚部分氧化重整制氢

二甲醚是一种理想的氢载体,可用于解决氢的储存和运输。以Pt/TiO_2为部分氧化催化剂,结合Ni/Al_2O_3重整催化剂,考察钛前驱体和焙烧温度对二甲醚部分氧化重整制氢反应的影响。结果表明,以Ti(C4H9O)4为原料制备的TiO_2为金红石相,Ti(SO4)2或Ti O(OH)2为原料制备的TiO_2为锐钛矿相;以Ti(C4H9O)4为原料制备的Pt/TiO_2-E催化剂催化性能略好,转化率接近100%,H2收率约90%,表明金红石相TiO_2负载的Pt催化剂略佳;以Ti(SO4)2为原料制备的Pt/TiO_2-S催化剂500℃焙烧可获得金红石相TiO_2。与Pt/Al_2O_3催化剂相比,Pt/TiO_2催化剂具有更好的催化性能,H2收率超过90%,而Pt/Al_2O_3催化剂H2收率约80%。     

氢气高温还原制备的负载型镍基催化剂用于苯酚加氢的性能

通过等体积浸渍法分别将Ni(NO₃)₂、NiCl₂、NiSO₄ 3种镍前体浸渍于A1₂O₃或SiO₂载体上,然后通过H₂高温还原法制备了负载型镍基催化剂,考察了镍前体、载体种类、镍负载量、反应条件等对镍基催化剂苯酚加氢性能的影响。结果表明,对比3种镍前体,在H₂高温还原体系中Ni(NO₃)₂最容易被还原,制备的镍基催化剂苯酚加氢活性最高。SiO₂负载的镍基催化剂活性远高于γ-Al₂O₃催化剂。适宜的Ni负载量有助于活性组分的分散和催化活性的提高。镍基催化剂的苯酚加氢产物以环己醇为主,相对缓和的反应条件更容易生成环己酮。在非极性溶剂正庚烷或环己烷存在下,苯酚加氢反应速率远远高于极性溶剂水或乙醇存在下的结果,而且环己酮的选择性更高。     

复合催化剂ZnFe2O4/FeVO4的制备及光催化性能

为了降解污水中的有机染料,对复合催化剂ZnFe₂O₄/FeVO₄光降解有机染料进行了研究,以促进水中生物的健康生长和整个生态系统的平衡。通过聚乙烯吡咯烷酮(PVP)辅助水热法制备出了ZnFe₂O₄,通过水热法制得了FeVO₄,并按照ZnFe₂O₄和FeVO₄不同质量比合成了复合催化剂ZnFe₂O₄/FeVO₄。以甲基橙为降解染料,在相同条件下对ZnFe₂O₄、FeVO₄和复合催化剂ZnFe₂O₄/FeVO₄进行活性对比实验,结果表明,所合成的复合催化剂ZnFe₂O₄/FeVO₄是一种高效率催化剂。通过扫描电子显微镜(SEM)分析,可以看出ZnFe₂O₄和FeVO₄复合在了一起。在加入H₂O₂的条件下反应20 min,ZnFe₂O₄和FeVO₄对甲基橙的降解率分别为15%和25%,而复合催化剂ZnFe₂O₄/FeVO₄对甲基橙的降解率可以达到75%。此外,以ZnFe₂O₄/FeVO₄为样品考察了催化剂用量、H₂O₂浓度和pH值对催化活性的影响,结果表明,ZnFe₂O₄/FeVO₄样品的最佳催化条件为:溶液pH=5.0、H₂O₂浓度为0.044 mol/L、催化剂用量为1.0 g/L。