微量Pt和Pd对Fe_2O_3/ZrO_2催化剂结构与性能的影响

用ＸＲＤ、ＴＰＲ及固定床微反应器技术研究了微量Ｐｔ 和Ｐｄ 对Ｆｅ２Ｏ３／ＺｒＯ２ 催化剂结构及性能的影响。结果表明，活性组分Ｆｅ３ ＋ 与载体ＺｒＯ２ 之间的相互作用会阻止载体从无定形ＺｒＯ２ 到ｔ－ＺｒＯ２ 进而ｍ － ＺｒＯ２ 的转变，同时，促进Ｆｅ２Ｏ３ 在ＺｒＯ２ 表面的分散。微量Ｐｔ 或Ｐｄ 的加入对Ｆｅ２Ｏ３ 在ＺｒＯ２ 上的分散状态无明显影响，但使Ｆｅ２Ｏ３／ＺｒＯ２ 的还原性能发生明显变化，表层Ｆｅ２Ｏ３ 的还原性显著增强，导致Ｍ－ Ｆｅ２Ｏ３／ＺｒＯ２ 催化剂在ＮＯ＋ ＣＯ反应中有更高的催化活性。Ｎ２ 生成的选择性次序为Ｆｅ２Ｏ３／ＺｒＯ２ ＞ Ｐｄ － Ｆｅ２Ｏ３／ＺｒＯ２ ＞ Ｐｔ－ Ｆｅ２Ｏ３／ＺｒＯ２ ＞ Ｐｄ／ＺｒＯ２ ＞ Ｐｔ／ＺｒＯ２ 。     

Fe/ZrO2催化剂的Mossbauer谱及XAFS表征

考察了经不同温度还原的Ｆｅ／ＺｒＯ２催化剂在ＣＯ２加氢制低碳烃反应中的催化活性,最佳结果为ＣＯ２转化率２７．０％,对Ｃ２＋烃的选择性５６．７％,采用ＸＲＤ,＾５７ＦｅＭｏｓｓｂａｕｅｒ谱,Ｆｅ－Ｋ－吸收边的Ｘ射线吸收近边结构（ＸＡＮＥＳ）及扩展Ｘ射线吸收精细结构（ＥＸＡＦＳ）等表征方法研究了催化剂的表面结构。结果表明,在ＺｒＯ２表面上主要存在α－Ｆｅ及配位不饱和的Ｆｅ＾３＋两种物种。催化剂表面明显呈氧缺位,零价铁相对富集的状态,还原温度对表面结构有显著的影响,最佳还原温度与表面Ｆｅ－Ｏ键的键长有关,结合这种催化剂在ＣＯ２加氢制低碳烃反应中的催化活性,认为α－Ｆｅ与配位不饱和的Ｆｅ＾３＋物种的协同作用是其具有较高催化活性的重要原因。     

锰助剂对Fe／ZrO2催化剂F—T反应催化性能的影响

应用ＸＲＤ，ＸＰＳ，Ｍｏｓｓｂａｕｅｒ谱，ＴＰＲ，ＣＯ化学吸附ＣＯ－ＴＰＤ，ＣＯ＋Ｈ２反应性能测试等手段研究了锰助剂对Ｆ－Ｔ合成制低碳烯烃Ｍｎ－Ｆｅ／ＺｒＯ２催化剂结构及催化性能的影响。结果表明，与Ｆｅ／Ｚｒ催化相比，加锰助剂后的催化剂Ｆ－Ｔ反应催化活性上升，甲烷选择性降低，低碳烯烃选择性增加。     

在涂层TiO2改性铜催化剂上甲醇脱氢制甲酸甲酯

在常压和２５０℃下，考察了涂层ＴｉＯ２改性铜催化剂上甲醇脱氢生成甲酸甲酯的活性和选择性以及催化剂的稳定性。结果表明，涂层ＴｉＯ２明显提高了铜催化剂的活性和稳定性。在所考察的铜催化剂中，以Ｃｕ／ＴｉＯ２／ＡｌＯ３的催化活性最高，甚至高于离子交换法制备的Ｃｕ（ｅｘ）／ＳｉＯ２催化剂。ＸＰＳ分析表明，Ｃｕ／ＴｉＯ２／ＡｌＯ３中存在着两种化学环境不同的ＣＵ（０），即负载在ｒ－ＡＬＯ３和ＴｉＯ２－Ａｌ２Ｏ３     

CH4,CO2和O2制合成气反应中载体对Ni催化剂抗氧化性能的影响

在ＣＨ４、ＣＯ２ 催化氧化制合成气反应中, Ｎｉ／Ａｌ２Ｏ３ 催化剂在高温下生成ＮｉＡｌ２Ｏ４ 尖晶石,是导致催化剂失活的一个重要因素． 通过向载体（Ａｌ２Ｏ３）中添加各种氧化物, 使得催化剂的抗氧化性能得到改善． 并运用ＴＰＲ、ＸＲＤ对催化剂进行表征, 发现催化剂的抗氧化性顺序为： Ｎｉ／ＣａＯ－Ａｌ２Ｏ３ ＞ Ｎｉ／ＭｇＯ－Ａｌ２Ｏ３ ＞ Ｎｉ／ＣｅＯ２－Ａｌ２Ｏ３ ＞ Ｎｉ／Ｌａ２Ｏ３－Ａｌ２Ｏ３ ＞ Ｎｉ／Ｙ２Ｏ３－Ａｌ２Ｏ３ ＞ Ｎｉ／ＴｉＯ２－Ａｌ２Ｏ３＞ Ｎｉ／Ａｌ２Ｏ３＞ Ｎｉ／Ｆｅ２Ｏ３－Ａｌ２Ｏ３．     

Fe_2O_3／ZrO_2催化剂上一氧化碳加氢反应制低碳烯烃 Ⅱ．预处理条件对催化剂结构及性能的影响

用ＴＰＲ，Ｍｏｓｓｂａｕｅｒ谱法，ＸＰＳ，ＸＲＤ及反应评价等手段研究了Ｆｅ２Ｏ３／ＺｒＯ２催化剂的还原行为、铁物种状态和ＣＯ加氢反应性能．结果表明，预处理条件明显影响Ｆｅ２Ｏ３／ＺｒＯ２催化剂表面铁原子的数量、铁锆间的相互作用、催化剂的物相变化以及ＣＯ加氢反应的催化性能．以Ｆｅ２Ｏ３／ＺｒＯ２经氢氟混合气程序升温至７５３Ｋ还原生成的Ｆｅ－Ｚｒ－Ｏ物种为前身，在合成气中进一步还原得到的铁锆催化剂，具有较好的Ｆ－Ｔ反应合成低碳烯烃的选择性．     

Fe_2O_3／ZrO_2催化剂上一氧化碳加氢反应制低碳烯烃──I．催化剂反应性能及反应过程中铁物相的变化

用浸渍法制得一系列不同铁负载量的Ｆｅ２Ｏ３／ＺｒＯ２催化剂，应用催化反应评价结合穆斯堡尔谱对催化剂的ＣＯ加氢反应性能、催化剂活性相结构及催化剂铁物种在合成气反应过程中的物相变化进行了研究．结果表明，铁负载量的大小对于Ｆｅ２Ｏ３／ＺｒＯ２催化剂的Ｆ－Ｔ反应催化性能有很大影响，铁负载量适当时，Ｆｅ２Ｏ３／ＺｒＯ２催化剂铁锆间适当的强相互作用使得催化剂在保持较高催化活性的同时高选择性地生成低碳烯烃，产物分布偏离Ｓｃｈｕｌｚ－Ｆｌｏｒｙ分布规律．     

氧化铈对F-T反应铁锆催化剂的助催化作用

应用ＸＲＤ、ＸＰＳ、Ｍｏｓｓｂａｕｅｒ谱、ＴＰＲ、ＣＯ－ＴＰＤ、ＣＯ＋Ｈ２反应性能测量试等手段研究了ＣｅＯ２对Ｆ－Ｔ合成制低碳烯烃Ｃｅ－Ｆｅ／ＺｒＯ２催化剂催化性能的影响。结果表明，与Ｆｅ／Ｚｒ催化剂相比，加铈助剂后的催化剂Ｆ－Ｔ反应催化活性明显上升。     

镧改性铁催化剂的研究Ⅲ.镧改性铁催化剂的表面吸附性能

用ＸＰＳ，ＩＲ和Ｃａｈｎ微量天平技术研究了Ｆｅ２Ｏ３／γ－Ａｌ２Ｏ３，Ｆｅ２Ｏ３－Ｌａ２Ｏ３／γ－Ａｌ２Ｏ３和Ｆｅ２Ｏ３／Ｌａ２Ｏ３／γ－Ａｌ２Ｏ３催化剂的表面吸附性能。结果表明，部分镧履盖了催化剂表面，这部分镧优先堵盖ＣＯ的桥式吸附位，同时由于部分镧的覆盖，减少了ＣＯ和Ｈ２的化学吸附量，但大大促进了（ＣＯ＋Ｈ２）的共吸附，提高了催化剂的再吸附能力。     

Fe2O3/ZrO2催化剂上一氧化碳加氢反应制低碳烯烃Ⅱ.预处理条件对催化剂结构及性能的影响

用ＴＰＲ，Ｍｏｓｓｂａｕｅｒ谱法，ＸＰＳ，ＳＲＤ及反应评价等手段了Ｆｅ２Ｏ３／ＺｒＯ２催化剂的还原行为，铁物种状态和ＣＯ加氢反应性能，结果表明，预处理条件明显影响Ｆｅ２Ｏ３／ＺｒＯ２催化剂表面铁原子的数量、铁锆间的相互作用，催化剂的物相变化以及Ｃ氢反应的催经性能，以Ｆｅ２Ｏ２／ＺｒＯ２经氢氩混合氯程序升温至７５３Ｋ还原生成的Ｆｅ－Ｚｒ－Ｏ物种为前身，在合成气中进一步还原得到的铁锆催化剂，具有较好的     

ZrO_2、TiO_2担载氧化铁催化剂上二氧化碳加氢制低碳烃(英文)

采用创新方法制备的ZrO2、TiO2担载氧化铁催化剂在二氧化碳加氢制低碳烃反应中显示出良好的催化活性和产物选择性,由15wt?/ZrO2给出的最佳结果为：CO2转化率为20%,除甲烷以外的低碳烃的选择性接近70%。还考察了金属Fe担载量及催化剂的预还原温度对催化活性的影响,发现催化活性随金属Fe担载量的增加而呈现“双峰”现象,这种现象可能与活性物种(零价铁及配位不饱和的三价或二价铁)在催化剂表面的几何排布有关,而两种催化剂的最佳还原温度分别为723 K(5wt?/ZrO2)和773 K(5wt?/TiO2)。     

焙烧及还原温度对 Co-Pt-ZrO2/γ-Al2O3催化剂费托合成反应性能的影响

采用浸渍法制备了Co-Pt-ZrO₂/γ-Al₂O₃催化剂,对其进行了BET、XRD和TPR等表征,并在浆态床反应器上考察了焙烧温度和还原温度对催化剂费托合成反应性能的影响。结果表明,焙烧温度过高,容易造成Co物种和载体间的相互作用增强,使部分氧化钴颗粒聚集或烧结,导致催化剂的F-T合成反应活性和C₅₊烃选择性降低。还原温度较低时,钴物种不能充分还原,CO加氢活性低,甲烷选择性高,重质烃选择性低;还原温度过高,则可能造成活性物种的烧结,反而降低了催化剂的活性和重质烃选择性。在原料气n(H₂)/n(CO)=2.0、483 K、2.4 MPa和空速3.6 L/(gcat·h)的条件下,31.08%Co～0.11%Pt～7.16%ZrO₂/Al₂O₃催化剂在673 K焙烧。纯H₂下653 K还原后,其费托性能最佳;CO转化率为27.0%,C₅₊的选择性为83.0%。     

Effects of pretreatment and reduction on the Co/Al2O3 catalyst for CO hydrogenation

The purpose of this study was to investigate the effect of preadsorbed CO at different temperatures, calcination temperatures, the combined influence of reduction temperature and time, and pretreatment using hydrogen or syngas as reduction agents on the F-T synthesis （FTS） activity and selectivity of Co/Al2O3 catalyst. The reactivity of the carbon species at higher preadsorption temperature with H2 in TPSR decreased, whereas the carbon-containing species showed higher reactivity over Co/Al2O3 catalyst with low calcination temperature. This agreed well with the order of catalytic activity for F-T synthesis on this catalyst. The catalytic activity of the catalyst varied with reduction temperature and time remarkably. CODEX optimization gave an optimum reduction temperature of 756 K and reduction time of 6.2 h and estimated C5＋ yield perfectly. The pretreatment of Co/Al2O3 catalyst with different reduction agents （hydrogen or syngas） showed important influences on the catalytic performance. A high CO conversion and C5＋ yield were obtained on the catalyst reduced by hydrogen, whereas methane selectivity on the catalyst reduced by syngas was much higher than that on the catalyst reduced by hydrogen.     

Effect of barium on reducibility and activity for cobalt-based Fischer-Tropsch synthesis catalysts

Barium modified Co/Al2O3 catalysts were prepared by incipient wetness impregnation. The catalysts were characterized by XRD, TPD and DRIFTS. The catalytic activity for Fischer-Tropsch synthesis was measured in a continuously stirred tank reactor. It was found that small amounts of BaO (≤ 2 wt%) improved the cobalt reducibility, which led to more cobalt active sites on the catalyst surface, and then resulted in higher CO conversion and C5+ selectivity. However, for the catalysts with high BaO loadings negative effects on the catalytic activity and selectivity for high hydrocarbons were observed because of low cobalt reducibility.     

CO_2加氢活性与担载铁催化剂表面Fe-O键强度的关系

采用浸渍 -还原法 ,制备了 Al2 O3、 Ti O2 、 Zr O2 担载铁催化剂 ,并在温度 6 2 3K、压力 1.5 MPa、空速80 0～ 10 0 0 h- 1、原料气组成 CO2 /H2 为 1∶ 2等实验条件下 ,考察了不同还原温度的催化剂在 CO2 加氢制低碳(C2 ～ C5 )烃中的反应活性 .结果表明 ,以 CO2 转化率计 ,各催化剂均存在最佳还原温度 (Fe/Al2 O3:873K;Fe/Ti O2 :773K;Fe/Zr O2 :72 3K) .将此温度与催化剂表面 Fe- O键强度相关联 ,发现在相同条件下 ,与载体 M-O键长有关的 Fe- O键越强 ,催化剂越容易被还原 ,最佳还原温度越低 ,反应活性越好 .     

Catalytic performance of Fe modified K/MO2C catalyst for CO hydrogenation

Fe modified and un-modified K/Mo2C were prepared and investigated as catalysts for CO hydrogenation reaction. Compared with K/Mo2C catalyst, the addition of Fe increased the production of alcohols, especially the C2+OH. Meanwhile, considerable amounts of C5+ hydrocar- bons and C2= -C4= were formed, whereas methane selectivity greatly decreased. Also, the activity and selectivity of the catalyst were readily affected by the reaction pressure and temperature employed. According to the XPS results, Mo4+ might be responsible for the production of alcohols, whereas the low valence state of Mo species such as Mo0 and/or Mo2+ might be account for the high activity and selectivity toward hydrocarbons.     

Fischer-Tropsch synthesis on anchored Co/Nb2O5/Al2O3 catalysts: the nature of the surface and the effect on chain growth

A series of Co/x%Nb2O5/Al2O3 catalysts were prepared by anchoring niobia on an Al2O3 support at different niobia concentrations. Characterization of the structure and nature of surface active sites was attempted in order to correlate the CO hydrogenation activity of these systems with those of the Co/Al2O3 and Co/Nb2O5 catalysts. The effect of the reduction temperature on the CO hydrogenation activity and selectivity was studied, showing that interaction of cobalt and niobia surface species favored the selectivity for hydrocarbon chain growth. However, this effect is less pronounced on the niobia-promoted Co/Al2O3 compared to Co/Nb2O5 catalysts. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy (DRS) results on Co/x%Nb2O5/Al2O3 showed prevailing amounts of Co2+ and Co3+ after calcination and reduction at 573 K, while, after reduction at 773 K, besides metallic cobalt, the Co2+ species still remains in contact with alumina, even for higher niobia loading. It seems that during this process formation and destruction of new interfaces involving Co0-NbOx sites takes place. Results suggest that Co0, Co0-Co2+, and Co0-NbOx are the active sites at the surface. The relative abundance of Co2+ species affects greatly the performance of the catalysts. DRIFTS and selectivity results suggest that these sites might be responsible for the reaction chain growth and therefore for the drastic change in the selectivity of CH4 and C5+ hydrocarbons mainly on the Co/Nb2O5 catalyst. DRIFTS results on Co/Nb2O5/Al2O3 showed the formation of -C=C- and -CH3- besides CHxO species. With increasing reduction temperature, the -C=C- species disappear while -CH3- fragments increased markedly, suggesting the formation of increasing amounts of hydrocarbons with higher chain length.     

Ni/Al2O3和Fe/Al2O3催化剂催化乙醇水蒸气重整制氢的对比研究

甲醇、乙醇等低碳醇催化重整制氢是燃料电池氢源的重要技术之一.乙醇和甲醇相比,更容易存储,低毒且可以从生物质经发酵获得[1,2].乙醇可以通过裂解、部分氧化、水蒸气重整和氧化重整等途径制氢[3~6].已有的文献表明,Pt、Ru、Rh、Pd等贵金属可有效地催化乙醇重整反应,载体多选用     

低硅铝比ZSM-5分子筛上C4烃的催化裂解反应

以低硅铝比(n(SiO2)/n(Al2O3)=20-45)的ZSM-5分子筛为催化剂, 研究了混合C4烃的催化裂解反应, 并对不同硅铝比的ZSM-5分子筛进行了酸性表征. 混合C4烃的催化裂解反应结果表明, 低硅铝比的ZSM-5分子筛具有较高的低温催化活性, 高硅铝比ZSM-5分子筛催化剂上乙烯和丙烯的收率高于低硅铝比ZSM-5分子筛催化剂, 低硅铝比ZSM-5分子筛上苯和甲苯的收率高于高硅铝比ZSM-5分子筛催化剂. 在反应温度为625 ℃时, 硅铝比为20的ZSM-5分子筛催化剂上乙烯、丙烯、苯和甲苯的总收率可达79.42%. 酸性表征结果表明, 硅铝比低的ZSM-5分子筛具有更多的Bronsted(B)酸酸量、Lewis(L)酸酸量及总酸酸量, 这是低硅铝比ZSM-5分子筛具有低温高活性及高的苯和甲苯收率的原因.     

EFFECTS OF BINDERS ON THE PRODUCTION OF LIGHT ALKENES FROM SYNGAS OVER K-Fe-MnO/SILICALITE-2 CATALYST I. EFFECT OF VARIOUS BINDERS ON CO HYDROGENATION

The performance of the K-Fe-MnO/Si-2 catalyst for the production of light olefins via Co hydrogenation changes obviously with the addition of binders. The results of CO hydrogenation. TPR, Mossbauer spectra CI0TPF, CO/H2-TPSR and C2H4/H2-TPSR are employed to investigate the effects of various binders on the physical-chemical states and catalytic behaviors of K-Fe-MnO/Si-2 catalyst to produce light olefins via syngas, TiO2 can promote the reduction of Fe and strengthen the adsorption of CO resulting in raising olefin selectivity. Other binders such as Al2O3, SiO2, MgO, once added into the catalyst, may cause formation of inorganic salts between FeO and Binders leading to a decrease of Fe reduction and a loss of olefin selectivity for CO hydrogenation. Especially, For K-Fe-MnO/Si-2 catalyst with Al2O3 binder directly, the strong secondary reactions of ethylene during CO hydrogenation cause a very poor light olefin selectivity, which will be improved greatly by modifying Al2O3.