二氧化硅负载钌催化剂催化氨硼烷水解产氢研究

采用浸渍-还原法制备了Ru/SiO₂催化剂,并考察了钌负载量、还原剂硼氢化钠的用量、还原温度以及反应条件对催化剂Ru/SiO₂催化BH₃NH₃水解产氢的影响。结果表明,在钌的负载量为0.1%（质量分数）、还原剂硼氢化钠与钌的物质的量比为2.2∶1、还原温度为303 K时制备的催化剂,催化BH₃NH₃水解产氢速率最快[转化频率TOF为140.8 L H₂/（mol Ru·min）]。搅拌转速为450 r/min时,氨硼烷向催化剂表面传质最快,产氢速率最大。氨硼烷水解反应由催化剂界面反应控制,产氢速率与催化剂用量成正比。随着反应温度的升高,Ru活化的氨硼烷分子能量增加,反应速率逐渐增加。反应动力学计算表明Ru/SiO₂催化剂催化BH₃NH₃水解产氢反应对氨硼烷浓度为零级反应,活化能为45 kJ/mol。     

膨润土负载钌催化剂制备及其催化氨硼烷水解产氢研究

采用浸渍-化学还原法制备了钌/膨润土（Ru/Ben）催化剂,考察了钌含量、还原剂硼氢化钠用量、还原温度以及反应条件等对Ru/Ben催化氨硼烷（NH₃BH₃）水解产氢的影响。结果表明,在钌负载量为0.3%（质量分数）、钌与还原剂硼氢化钠物质的量比为1∶2.5、还原温度为303 K条件下,制备的Ru/Ben中Ru微晶尺寸为3.8 nm,Ru/Ben催化NH₃BH₃水解产氢的转化频率（TOF）为145 mol/（mol·min）;搅拌转速为450 r/min时,外扩散限制消除,产氢速率最大;产氢速率与Ru/Ben浓度成正比,催化剂界面反应是氨硼烷水解产氢反应的控速步骤,Ru/Ben催化NH₃BH₃水解产氢反应对催化剂浓度的反应级数为0.7;反应温度越高,氨硼烷向催化剂表面的传质速率越高、产物氢气及副产物偏硼酸钠从催化剂表面越易脱附,产氢速率越大。动力学计算表明,Ru/Ben催化NH₃BH₃水解产氢反应的产氢速率与氨硼烷浓度无关,活化能为15 kJ/mol。     

ZIF-67及其母液衍生Co3O4催化氨硼烷水解制氢

采用常规液相沉淀反应合成了沸石咪唑酯金属有机骨架化合物ZIF-67,并对母液进行浓缩结晶以回收钴基化合物。通过高温焙烧的方式将ZIF-67及其母液转化为2种Co₃O₄(记作Co₃O₄-S和Co₃O₄-L)作为氨硼烷水解的催化剂前驱体。考察了反应液中氨硼烷浓度、催化剂浓度和反应温度对体系产氢速率的影响,并进行动力学分析。结果表明:Co₃O₄-S为多孔多面体结构而Co₃O₄-L为纳米颗粒;增加反应液中氨硼烷浓度和催化剂浓度有助于提升体系的产氢速率;经4次循环使用后,Co₃O₄-S催化产氢速率无衰减,Co₃O₄-L催化产氢速率为初始值的78%。     

竹茹丝炭负载钌催化剂光催化氨硼烷水解产氢研究

为了制备高效、低成本的氨硼烷制氢催化剂，以竹茹丝为原料，采用直接煅烧法得到竹茹丝炭材料(BSC)，再以BSC为载体通过浸渍-还原法将金属Ru负载到载体表面，制备出层状结构的Ru/BSC催化剂。通过各种表征方法对催化剂的结构组成和形貌进行了分析并探究了光与非光、金属负载量、催化剂用量、氨硼烷浓度、温度等条件对氨硼烷水解产氢的影响。结果表明，Ru与BSC之间存在金属-载体相互作用，1.0%Ru/BSC催化剂在可见光照射下催化氨硼烷水解产氢性能明显优于非光条件，氨硼烷水解产氢速率与Ru/BSC催化剂用量成正比，与氨硼烷浓度无关。计算得到1.0%Ru/BSC在298 K时光催化反应的转化频率(TOF)为446.4 min^-1、活化能为64.0 kJ/mol。因此，该研究为制备高效且低成本的催化剂提供了新的思路。     

自搅拌下CoB/SiO2催化剂催化硼氢化钠水解制氢研究

采用浸渍-化学还原法制备了硼化钴/二氧化硅（CoB/SiO₂）催化剂,并考察了其催化硼氢化钠水解制氢的性能。研究了二氧化硅粒径、硝酸钴与二氧化硅物质的量比、硝酸钴与硼氢化钠物质的量比等条件对催化剂性能的影响,进而考察了催化剂用量、搅拌转速、反应温度等条件对硼氢化钠水解制氢性能的影响。结果表明,在二氧化硅粒径为15 nm、硝酸钴与二氧化硅物质的量比为0.08∶1、硝酸钴与硼氢化钠物质的量比为1∶5条件下,制备的催化剂催化硼氢化钠水解产氢的速率为45.6 mL/（min·g）;因为催化剂粒径很小,伴随硼氢化钠水解产氢产生的动量可以完全消除外扩散速率的影响,搅拌转速对硼氢化钠水解速率的影响很小,硼氢化钠的水解速率随着催化剂用量的增加而增大;随着温度的升高,硼氢化钠的水解速率增大,硼氢化钠水解反应的表观活化能为48.54 kJ/mol,硼氢化钠反应级数为零;催化剂具有良好的重复使用性能和稳定性。     

钴-硼/二氧化锆催化剂催化硼氢化钠水解制氢研究

采用浸渍负载-还原法制备了钴-硼/二氧化锆催化剂,研究了催化剂在催化硼氢化钠水解制氢中的性能。研究了催化剂的制备条件（钴与二氧化锆物质的量比、钴与硼氢化钠物质的量比）对其催化性能的影响,并考察了催化剂用量、反应温度、搅拌转速对硼氢化钠水解制氢的影响。结果表明,在钴与二氧化锆物质的量比为0.16:1、钴与硼氢化钠物质的量比为1:5条件下制备的钴-硼/二氧化锆催化剂催化硼氢化钠水解制氢的速率最快。硼氢化钠水解制氢速率随催化剂用量的增加和反应温度的升高而增大,随搅拌转速的增加呈现先增大后减小的趋势。反应动力学计算出钴-硼/二氧化锆催化剂催化硼氢化钠水解对硼氢化钠的浓度属于零级反应。钴-硼/二氧化锆催化剂的硼氢化钠水解反应活化能为43.97 kJ/mol。     

氨硼烷水解制氢研究进展

氢能是替代传统化石能源的重要清洁能源,然而实现氢能的高质量密度储存与温和条件下快速释放仍是一大瓶颈。氨硼烷储氢密度高达19.6%（质量）,在室温下水解即可制得氢气,是最有发展前景的储氢材料之一。然而氨硼烷在水中放氢速度缓慢,因此开发加速其水解过程的催化剂至关重要。对氨硼烷的水解催化剂的研究主要集中在金属单质、金属化合物与光催化剂三类材料。本文从实践方面,介绍了氨硼烷水解制氢的研究方法,从理论方面,通过介绍催化剂的发展,综述了氨硼烷水解反应的步骤与机理。通过对产氢过程的深入描述,介绍了对氨硼烷水解制氢反应正面调控的方法,并依据已有的研究提出了未来该类催化剂的设计策略。     

Fe2O3/AC催化剂上对甲基苯硫酚的水相催化氧化偶联

以对甲基苯硫酚为模型底物，空气为氧化剂，来研究硫醇水相催化氧化偶联制备二硫醚。以活性炭为载体，采用等体积浸渍法制备了一系列负载型氧化物催化剂，并考察了其在对甲基苯硫酚氧化偶联制备对甲苯二硫醚反应中的催化性能。反应结果表明，活性炭负载的铁氧化物具有最佳催化性能。采用N₂物理吸附、X射线衍射、X射线光电子能谱和透射电镜等表征手段对活性炭负载的铁氧化物催化剂进行了表征。表征结果表明，铁氧化物为高度分散在活性炭上的Fe₂O₃物种。以Fe₂O₃/AC为催化剂，当催化剂焙烧温度为400℃，Fe负载量为5%，在50℃下反应30min时，对甲苯二硫醚的收率高达97.4%；该催化剂循环使用5次后活性无明显下降。     

Fe3O4负载催化剂上双环戊二烯氢甲酰化

采用共沉淀法制备系列铁磁性氧化物负载的钴、铑及钴铑双金属催化剂。研究以三苯基膦改性的Co/Fe₃O₄、Rh/Fe₃O₄和Co-Rh/Fe₃O₄催化剂对双环戊二烯氢甲酰化合成三环癸烷二甲醛的催化性能,并对催化剂进行XRD、FT-IR和TPR等表征。结果表明,Co-Rh/Fe₃O₄催化剂对双环戊二烯氢甲酰化合成三环癸烷二甲醛具有最高的选择性。双环戊二烯氢甲酰化合成三环癸烷二甲醛的过程与反应压力、催化剂与双环戊二烯的质量比、反应温度和溶剂的种类有关。增加催化剂与双环戊二烯质量比和升高温度及压力有利于双环戊二烯的转化和三环癸烷二甲醛选择性,采用极性相对较小的溶剂有利于三环癸烷二甲醛的形成。催化剂重复使用5次,催化活性几乎不变。 在催化剂与双环戊二烯质量比为2∶15、Rh的负载量为1∶100、反应温度140 ℃、反应压力7 MPa和反应时间5 h条件下,双环戊二烯转化率达99%以上,三环癸烷二甲醛选择性达60%以上,进一步延长反应时间至12 h,三环癸烷二甲醛选择性超过90%。     

Cr掺杂的Co-B非晶态合金的制备及催化硼氢化钠水解制氢

采用化学还原法制备了三元非晶态Co-Cr-B纳米催化剂。采用透射电镜（TEM）、扫描电镜（SEM）、X射线衍射仪（XRD）等测试方法对催化剂的形貌、结构、成分做了表征。通过排水法进行NaBH₄溶液水解产氢反应,测量了催化剂的催化性能。结果表明,当掺杂少量的Cr时,催化剂的粒径明显减小,比表面积明显增大,催化剂的性能提高。过量的Cr会导致出现过多的氧化物和Cr ³⁺,覆盖了催化剂表面活性位点,降低催化剂的性能。当Cr与Co物质的量比为0.005时,催化剂性能最佳。与纯Co-B相比,其对硼氢化钠水解产氢速率提高了2倍。此外,研究了催化剂用量、NaBH₄浓度、反应温度、NaOH浓度等因素对NaBH₄溶液水解产氢反应的影响。     

Transition metal-doped heteropoly catalysts for the selective oxidation of methacrolein to methacrylic acid

Heteropoly compounds with the general formula Cs₁M_0.5^x+H_3?0.5xP_1.2Mo₁₁VO₄₀ (M= Fe, Co, Ni, Cu or Zn) and Cs₁Cu_yH_3?2yP_1.2Mo₁₁VO₄₀ (y = 0.1, 0.3 or 0.7) were synthesized and then used as catalysts for the selective oxidation of methacrolein to methacrylic acid. The effects of the transition metals on the structure and activity of the catalysts were investigated. FTIR spectra showed that the transition metal-doped catalysts maintained the Keggin structure of the undoped catalysts. X-ray diffraction results indicated that before calcination, the catalysts doped with Fe and Cu had cubic secondary structures, while the catalysts doped with Co, Ni or Zn had both triclinic and cubic phases and the Co-doped catalyst had the highest content of the triclinic form. Thermal treatment can decrease the content of the triclinic phase. NH₃ temperature-programmed desorption and H₂ temperature-programmed reduction results showed that the transition metals changed the acid and redox properties of the catalysts. The addition of Fe or Cu had positive effects on the activities of the catalyst which is due to the improvement of the electron transfer between the Fe or Cu and the Mo. The effects of the copper content on structure and catalytic activity were also investigated. The Cs₁Cu_0.3H₂P_1.2Mo₁₁VO₄₀ catalyst had the best performance for the selective oxidation of methacrolein to methacrylic acid.     

N2O catalytic decomposition over various spinel-type oxides

Various spinel-type catalysts AB₂O₄ (where A = Mg, Ca, Mn, Co, Ni, Cu, Cr, Fe, Zn and B = Cr, Fe, Co) were prepared and characterized by XRD, BET, TEM and FESEM-EDS. The performance of these catalysts towards the decomposition of N₂O to N₂ and O₂ was evaluated in a temperature programmed reaction (TPR) apparatus in the absence and the presence of oxygen. Spinel-type oxides containing Co at the B site were found to provide the best activity. The half conversion temperature of nitrous oxide over the MgCo₂O₄ catalyst was 440 °C and 470 °C in the absence and presence of oxygen, respectively (GHSV = 80,000 h⁻¹).

On the grounds of temperature programmed oxygen desorption (TPD) analyses as well as of reactive runs, the prevalent activity of the MgCo₂O₄ catalyst could be explained by its higher concentration of suprafacial, weakly chemisorbed oxygen species, whose related vacancies contribute actively to nitrous oxide catalytic decomposition. This indicates the way for the development of new, more active catalysts, possibly capable of delivering at low temperatures amounts of these oxygen species even higher than those characteristic of MgCo₂O₄.     

Mechano-catalytic overall water splitting on some mixed oxides

Simple transition metal oxides such as NiO, Co₃O₄, Fe₃O₄ and Cu₂O were found to catalytically decompose water into H₂ and O₂ by mechanical energy. The reaction is regarded as “mechano-catalytic” overall water splitting” and is a quite novel catalytic reaction. In this paper, some general aspects on the mechano-catalytic overall water splitting are reviewed on simple oxides. In addition, recent results on the mechano-catalytic activity of a groups of mixed oxides, wolramite-type oxides with a formula of ABO₄ (A=Fe, Co, Ni and Cu, etc., B=W, Mo), are shown. AWO₄ (A=Fe, Co, Ni and Cu) decomposed water into H₂ and O₂ under the supply of mechanical energy, indicating that mechano-catalytic overall water splitting proceeded on wolframite-type compounds containing 3d-transition metals. AMoO₄ (A=Fe, Co, Ni) also decomposed water into H₂ and O₂ under supply of mechanical energy. The reaction properties on wolframite-type oxides are discussed.     

FeM双金属用于甲烷催化裂解制纯氢气和碳纳米材料

采用熔融法以铁、钼、铜和钨硝酸盐为原料,制备出一系列的Fe_xM_y（M=Mo、Cu、W）双金属催化剂。首先考察了一系列的Fe₁₅M₁（M=Mo、Cu、W）双金属催化剂的甲烷催化裂解（CDM）活性,Fe₁₅Mo₁的催化活性远高于Fe₁₅Cu₁和Fe₁₅W₁。通过比表面积测试（BET）、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）和拉曼光谱（Raman）等分析方法对Fe₁₅M₁的物理特性、结构组成、还原特性和副产物碳纳米材料（CNMs）的石墨化度等进行表征。进一步考察了金属Mo的掺杂量和焙烧温度对Fe_xMo_y双金属催化剂的甲烷转化率和碳产率的影响。Fe₁Mo₁表现出优异的催化性能,其碳产率（6g_C/g_cat）高于纯Fe的碳产率（4.35g_C/g_cat）。XRD和X射线光电子能谱（XPS）分析表明,Fe₁Mo₁双金属形成Fe₂(MoO₄)₃相,提高了其催化活性和稳定性;透射电镜（TEM）结果表明,Fe₁Mo₁催化剂CDM反应后的CNMs为竹节状的碳纳米管。     

Catalytic decomposition of N2O over monolithic supported noble metal-transition metal oxides

The decomposition of nitrous oxide to nitrogen and oxygen using a series of monolithic (ceria-alumina washcoated cordierite) supported transition metal (Cu, Fe, Co, Ni, Mn) and noble metal (Ir, Rh) oxide catalysts has been studied using gas chromatography. The effect of combining a transition metal with a noble metal has also been investigated. A synergetic effect was observed between transition metal and noble metal oxides in the presence of a small amount of water for some of the catalysts. The synergy between Fe-Ir and Ni-Ir was also verified under dry conditions. X-ray photoelectron spectroscopic measurements on these catalysts indicate that Fe, Rh and Ir are present predominantly as Fe₂O_3, RhO₂ and IrO₂, while significant amounts of Co and Ni ions may migrate inside the support to form cobalt and nickel aluminate. Only the Fe-Ir catalyst showed a significant interaction between the noble metal and the transition metal. The effect of water, oxygen and carbon monoxide on the catalytic behaviour of the five most active catalysts (Ni-Ir, Ni-Rh, Fe-Ir, Co-Ir, Ir) has also been investigated. Oxygen and water were found to inhibit the catalytic activity, although the extent of oxygen inhibition is limited, presumably due to the presence of ceria in the monolith washcoat support. Conversely, carbon monoxide greatly enhances catalytic activity.     

Co-Cu-Ce-Fe/γ-Al_2O_3催化剂催化分解N_2O的性能

以等体积浸渍法制备γ-Al_2O_3负载的Co、Cu、Ce和Fe氧化物催化剂,利用正交试验设计实验条件,采用XRD、BET和H_2-TPR等对催化剂进行表征,并考察活性组分对催化剂催化分解N_2O活性的影响。结果表明,催化剂具有尖晶石结构,其BET比表面积随着金属氧化物负载量增加而降低。催化剂中铜的氧化物可以降低还原峰温度,进而明显提高催化活性,Co和Fe的加入对活性有一定的提高,Ce对催化活性没有明显影响。     

氨分解制氢催化剂研究进展

随着环保法规日趋严格,清洁氢能的生产和应用引起关注,氨分解制氢是其中重要途径之一。综述Ru、Ni和Fe等氨分解催化剂的研究进展,Ru催化剂具有较高的催化活性,但由于资源有限和价格昂贵等因素使其在工业应用方面受到限制。以Fe和Ni为代表的非贵金属催化剂资源丰富,价格低廉,氨分解反应转化率高,具有潜在的工业应用前景。我国独创的新一代Fe_(1-x)O基新型熔铁催化剂是目前世界上活性最高的氨合成催化剂,根据微观可逆性原理,新型熔铁催化剂也是氨分解反应活性最好的制氢催化剂。     

An investigation of alumina-supported catalysts for the selective catalytic oxidation of ammonia in biomass gasification

Alumina-supported catalysts containing different transition metals (Ni, Cu, Cr, Mn, Fe and Co) were prepared and tested for their activity in the selective oxidation of ammonia reaction at high temperatures (between 700 and 900 °C) using a synthetic gasification gas mixture. The catalysts were also characterised for their acidic properties by infrared studies of pyridine and ammonia adsorption and reaction/desorption. The Ni/Al₂O₃ and Cr/Al₂O₃ catalyst displayed the highest selective catalytic oxidation (SCO) activity in that temperature range with excellent N₂ selectivities. FT-IR studies of adsorbed pyridine and NH₃ indicate that Lewis acid sites dominate and that NH₃ adsorption on these sites is likely to be the first step in the SCO reaction. FT-IR studies on less active catalysts, particularly on Cu/Al₂O₃ allowed the detection of oxidation intermediates, amide (NH₂), and possibly hydrazine and imido and nitroxyl species. The amide and hydrazine intermediate gives credence to a proposed SCO mechanism involving a hydrazine intermediate, while the proposed imide, =N–H, and/or nitroxyl, HNO species could be intermediates in incomplete oxidation of NH₃ to N₂O.     

磁性CuO-Bi2O3/Fe3O4-SiO2-MgO催化剂的制备及甲醛乙炔化性能

采用浸渍法和共沉淀法制备了一系列不同Cu含量的超顺磁CuO-Bi₂O₃/Fe₃O₄-SiO₂-MgO催化剂。使用电感耦合等离子体发射光谱仪(ICP-AES)、低温N₂物理吸-脱附、X射线衍射(XRD)、H₂程序升温还原(H₂-TPR)、振动样品磁强计(VSM)对催化剂的组成、结构、织构及磁性能进行表征, 评价了该催化剂催化甲醛乙炔化合成1, 4-丁炔二醇的催化活性。结果表明, 制备方法对催化剂中活性组分CuO的存在状态及炔化性能有较大影响, 采用共沉淀法较浸渍法制备的催化剂具有更高的比表面积、CuO分散度与较好的还原能力, 表现出较高的炔化性能;Cu含量是影响催化剂炔化性能的另一重要因素, 随Cu含量的增加, 催化剂活性逐渐增加, 在本研究考察范围内, 以共沉淀法制备的Cu质量分数为30%的催化剂表现出最佳的甲醛乙炔化性能。同时, 该催化剂具有良好的超顺磁性, 可以在外加磁场的作用下迅速分离回收, 循环使用6次后, 其催化活性明显高于非磁性催化剂。