Ni2P催化剂的制备及其在加氢脱硫的研究进展

现在油品重质化越来越严重,为了满足环境保护局和人们的要求,对油品加氢脱硫已是一项急迫的任务。过渡金属磷化物具有优异的加氢脱硫活性和稳定性,尤其是Ni2P催化剂,将成为催化材料领域研究的热点。本文综述了Ni2P催化剂制备方法和加氢脱硫活性。Ni2P催化剂有望成为继硫化物、碳化物催化剂之后的又一代深度加氢脱硫催化剂。     

Ni2P/TiO2上噻吩加氢脱硫性能研究

在10%H2/N2流动气氛下,用程序升温还原方法由相应的磷酸盐合成了二氧化钛负载磷化镍(Ni2P/TiO2)催化剂,用X射线衍射(XRD)、低温N2吸附(BET)等技术对催化剂的结构和性质进行了表征,在高压连续流动固定床反应装置上以噻吩为模型化合物,考察该催化剂的制备条件对其加氢脱硫性能的影响.结果表明,由Ni/P摩尔比为1/2和1/3的前驱体制备的催化剂表面仅出现Ni2P物相;由Ni/P摩尔比为1/1的前驱体制备的催化剂表面出现的主要物相为Ni2P,同时还存在少量Ni12P5相.催化剂的比表面积随前驱体中Ni和P含量的增加而减小.在温度370℃,压力3.0 MPa,VHSV为2 h-1,氢油比(v/v)为450的反应条件下,由Ni负载量为15%(wt)、Ni/P摩尔比为1/2的前驱体所制得Ni2P/TiO2催化剂对含硫0.1%(wt)油具有接近100%的脱硫转化率,并有良好的稳定性.加氢脱硫反应工艺条件研究结果表明:压力、液时进料体积空速以及氢油比对Ni2P/TiO2催化剂对噻吩加氢脱硫性能影响在较宽的范围内变化不大.反应温度对该催化剂上的噻吩加氢脱硫反应的影响较大,当反应温度高于300℃,催化剂对噻吩加氢脱硫性能达到接近100%的脱硫率.     

Ni_2P加氢脱硫催化剂的研究进展

简述了Ni2P催化剂的结构与加氢脱硫机理,以及Ni2P催化剂的3种制备方法:程序升温还原法、液相法和次磷酸盐热分解法。重点介绍了近年来Ni2P催化剂载体的研究情况,指出开发高效节能的新型加氢脱硫催化剂具有重要意义。     

分子筛负载型加氢脱硫催化剂的制备及其性能

采用溶胶-凝胶法低温一步合成了2种纳米介孔分子筛,对合成的样品进行了表征,并将其分别负载30% Ni2P(Co2P),将该催化剂用于噻吩加氢脱硫实验,考察了其加氢脱硫性能及稳定性. 结果表明,样品具有介孔特性,晶粒粒径约30 nm,孔径集中在20 nm左右,比表面积为400 m2/g,有一定弱酸性,有较好的热稳定性. 4种催化剂的第一次加氢脱硫率以CTAC为模板剂的载体比以CTAB为模板剂的载体高,以Co2P为活性组分比Ni2P高,低温比高温高. 4种催化剂第二次加氢脱硫率都有较大程度的降低,以Ni2P为活性组分的催化剂减少比Co2P高,360℃比300℃高,以CTAB为模板剂所制催化剂减少比CTAC高.     

还原终温对磷化物催化剂加氢脱硫反应性能的影响

以全硅MCM-41为载体,制备负载Ni2P和Mop型催化剂,考察了还原终温对催化剂制备和加氢脱硫反应性能的影响.对于Ni2P/MCM-41,NiO负载质量分数为12%,通过XRD和加氢脱硫反应评价得出最佳还原终温为500℃;对于MoP/MCM-41,MoO3负载质量分数为40%,通过XRD和加氢脱硫反应评价得出最佳还原...     

CeO2改性的Ni2P催化剂加氢脱硫反应性能

以二苯并噻吩（DBT）的十氢萘溶液（DBT质量分数为0．8％）为模型化合物,考察了CeO2改性的Ni2P催化剂加氢脱硫（HDs）反应性能,并用X射线衍射（xRD）和程序升温还原（TPR）对催化剂进行了表征。XRD结果表明,CeO2的引入抑制了Ni5P4杂晶的生成,Ni2P催化剂的晶粒尺寸随CeO2含量的增加而降低。TPR结果显示,在CeO2与Ni2P催化剂前驱体之问存在较强的相互作用,虽然抑制了NiO的还原,但促进了Ni2P物种的生成。从DBT的HDS反应结果可以看出,CeO2对于Ni2P加氢脱硫催化剂是一种有效的助剂,它的引入同时促进了Ni2P催化剂直接脱硫（DDS）和加氢（HYD）路径反应活性,从而提高了催化剂HDS活性。其中,催化剂的HYD反应活性随CeO2含量的变化规律与催化剂晶粒尺寸变化规律相似,说明Ni2P催化剂HYD反应活性对催化剂结构变化较为敏感。     

Ni2P/TiO2的制备、表征及其加氢脱硫反应性能

利用程序升温还原方法合成了Ni2P／TiO2催化剂，采用H2-TPR、XRD、XPS等技术对样品的结构和性质进行了表征，研究了催化剂对噻吩的常压加氢脱硫反应性能。结果表明，在TiO2为载体的负载型催化剂上，Ni2P为主要活性相，无明显的单质Ni相；与Ni2P／SiO2相比，Ni2P／TiO2催化剂对噻吩常压加氢脱硫反应有较高的转化率以及良好的稳定性，噻吩稳定转化率达到了36％左右。     

氢等离子体法制备Ni_2P和Ni_2P/SiO_2加氢脱硫催化剂

采用免焙烧的方法,直接将Ni(NO3)2和(NH4)2HPO4盐的前驱体,或是担载Ni(NO3)2和(NH4)2HPO4盐的前驱体通过氢等离子体法(PR)制备了Ni2P-NC-PR,Ni2P(25)/Si O2-NC-PR加氢脱硫催化剂。以质量分数为0.8%的二苯并噻吩/十氢萘溶液为模型化合物,考察了催化剂的HDS反应性能,并用XRD对催化剂晶相进行了表征。新鲜制备的催化剂在移入固定床反应器之前用体积分数10%H2S/Ar钝化,以保护其结构不被破坏。实验证明,PR还原法制备的Ni2P-NC-PR催化剂的加氢脱硫活性高于Ni2P-C-PR催化剂,PR还原法制备的Ni2P(25)/Si O2-NCPR催化剂的加氢脱硫活性高于Ni2P(25)/Si O2-C-PR催化剂。XRD表征结果表明:Ni2P-NC-PR或Ni2P(25)/Si O2-NC-PR催化剂的颗粒尺寸都小于Ni2P-C-PR或Ni2P(25)/Si O2-C-PR催化剂的颗粒尺寸,催化剂的活性中心较多,其高活性可归于其活性中心数量的增加。     

Ni2P催化剂的制备及加氢脱硫性能研究

通过共沉淀并用原位程序升温还原的方法制备了体相Ni2P催化剂,用二苯并噻吩(DBT)作为模型化合物进行加氢脱硫(HDS)活性评价,结果显示Ni2P具有比较低的加氢活性和相对高的脱硫活性,且有很高的稳定性。     

乙二醇对NiMoP/Al2O3上二苯并噻吩加氢脱硫反应的影响

在NiMoP浸渍液中添加不同含量乙二醇,制备了一系列NiMoP/Al2O3催化剂,以二苯并噻吩为模型化合物,考察有机添加剂乙二醇对NiMoP/Al2O3催化剂加氢脱硫性能的影响.结果表明,乙二醇的加入显著提高催化剂的加氢脱硫性能,乙二醇中的羟基与Ni物质的量比为5∶1时,催化剂的加氢脱硫活性最高.乙二醇明显改善NiMoP/Al2O3催化剂的加氢性能.     

Al2O3-ZrO2负载Ni2P催化剂加氢脱硫脱氮活性

采用浸渍-沉淀法制备Al2O3-ZrO2复合氧化物,通过程序升温还原法制备Ni2P/Al2O3-ZrO2催化剂。运用X射线衍射、N2吸附-脱附、X射线光电子能谱技术对载体和催化剂进行表征,并以噻吩加氢脱硫、吡啶加氢脱氮反应为探针考察复合氧化物对Ni2P催化剂加氢活性的影响。结果表明,在Al2O3表面引入少量ZrO2,既保持了γ-Al2O3大比表面积的结构优势,又减少了P或Ni与Al2O3表面的接触,促进Ni2P的形成。载体中ZrO2质量分数20%的Ni2P/Al2O3-ZrO2催化剂活性最高,载体焙烧温度过高会导致催化剂活性下降。     

Hydrodesulfurization of dibenzothiophene over alumina-supported nickel molybdenum phosphide catalysts

The activity of nickel molybdenum phosphide catalysts was studied for the hydrodesulfurization of dibenzothiophene at 573 K and total pressure of 2.0 MPa. The Al₂O₃-supported NiMo phosphide catalysts were prepared by successive and simultaneous methods. The effect of the reduction temperature on the catalyst activity was also studied. The simultaneous preparation was determined to be the best method for the preparation of the active supported catalyst for dibenzothiophene HDS. The 623 K-reduced catalyst had the highest HDS rate of the catalysts. Nickel migrated from the inside to the surface during the reaction and promoted the HDS activity. The active species in the dibenzothiophene HDS and the oxidation states of Mo, Ni and P in the catalyst before and after reaction and of S after the reaction were studied on the basis of an XPS analysis.     

原油深度加氢复合多金属硫化物催化剂的制备方法

复合多金属硫化物（MMS）催化剂主要用于原油的深度加氢,用于生产高十六烷值、低硫和低芳族化合物柴油。MMS催化剂包含NiMoS、NiWS、NiMoO、NiWO、NiMoWS和ZnMoWS催化剂等。综述MMS催化剂中二元复合金属硫化物催化剂和三元复合金属硫化物催化剂的制备方法,采用二步法即添加有机物作孔成形剂先制得催化剂前驱体,再由前驱体制得的MMS催化剂结构更松散,具有较大的比表面积（90 m²·g^-1）和大孔容（大于0.3 cm³·g^-1）,因而具有更好的催化活性。对比不同MMS催化剂对重质柴油、焦油等的加氢裂解、加氢脱硫和加氢脱氮性能,认为NiMoW三元复合金属硫化物催化剂(50%Ni25%Mo25%W)的活性最优。     

Unprecedented selectivity to the direct desulfurization (DDS) pathway in a highly active FeNi bimetallic phosphide catalyst

The hydrodesulfurization (HDS) of the refractory compound 4,6-dimethyldibenzothiophene (DMDBT) normally proceeds through a hydrogenation pathway that removes the planarity of the ring system and makes the hindered sulfur atom more accessible to the desulfurization centers. In this study, a highly active dispersed bimetallic NiFeP catalyst is found to have high selectivity for a direct desulfurization pathway, which does not require prior hydrogenation. The compound has equal numbers of Ni and Fe atoms which extended X-ray absorption fine structure analysis indicates are distributed randomly in the hexagonal Fe₂P structure, with just a slight enrichment of Fe on the surface. This is supported by density functional theory calculations. The remarkable properties of the catalyst are ascribed to a ligand effect of Fe on the active Ni atoms.     

器外预硫化型加氢催化剂的制备与性能研究

以Ni和Mo为活性组分,Al2O3为载体,制备了氧化型Ni-Mo/Al2O3催化剂O-1,在此基础上,以自制的水溶性复合硫化物为硫化剂,制备了器外预硫化型Ni-Mo/Al2O3催化剂S-1,通过BET、XRD和HRTEM等手段对2种催化剂的物化性质做了表征,并对比考察了催化剂对劣质石脑油加氢脱硫脱氮的性能。结果表明：器外预硫化型催化剂对劣质石脑油加氢脱硫脱氮的性能与氧化型催化剂接近,其加氢石脑油产品的硫氮含量均低于0.5 μg/g,这说明采用水溶性复合硫化物为硫化剂可以对氧化型催化剂进行有效地器外预硫化。     

Preparation of highly active MCM-41 supported Ni2P catalysts and its dibenzothiophene HDS performance

Highly active MCM-41 supported nickel phosphide catalysts for hydrodesulfurization(HDS) were synthesized by two different phosphorus sources, in which the surface of Ni_2P catalysts were modified by air instead of being passivated by O_2/N_2 mixture. In addition, the catalysts need not be activated with flowing H_2(30 ml·min~(-1))at 500 °C for 2 h prior to reaction as traditional method. X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), N_2-adsorption specific surface area measurements and CO chemisorption were used to characterize the resulting catalysts. The effect of modification with air on the surface of the catalysts for HDS performance was investigated. Results showed that the surface modification with air can promote the formation of smaller Ni_2P particles and more active Ni sites on surface of catalysts. At 3.0 MPa and 613 K, the dibenzothiophene(DBT)conversion of the catalysts modified with air was 98.7%, which was 7.1% higher than that of catalyst passivated by O_2/N_2 mixture. The higher activities of Ni_2P(x)/M41-O catalysts can be attributed to the smaller Ni_2P particles sizes and the increased hydrogen dissociation activity due to the surface modification.     

MgO-supported Mo, CoMo and NiMo sulfide hydrotreating catalysts

The most common preparation of high surface area MgO (100–500 m² g⁻¹) is calcination of Mg(OH)₂ obtained either by precipitation or MgO hydration or sol–gel method. Preparation of MoO₃/MgO catalyst is complicated by the high reactivity of MgO to H₂O and MoO₃. During conventional aqueous impregnation, MgO is transformed to Mg(OH)₂, and well soluble MgMoO₄ is easily formed. Alternative methods, that do not impair the starting MgO so strongly, are non-aqueous slurry impregnation and thermal spreading of MoO₃. Mo species of MoO₃/MgO catalyst are dissolved as MgMoO₄ during deposition of Co(Ni) by conventional aqueous impregnation. This can be avoided by using non-aqueous impregnation. Co(Ni)Mo/MgO catalysts must be calcined only at low temperature because Co(Ni)O and MgO easily form a solid solution. Literature data on hydrodesulfurization (HDS) activity of MgO-supported catalysts are often contradictory and do not reproduced well. However, some results suggest that very highly active HDS sites can be obtained using this support. Co(Ni)Mo/MgO catalysts prepared by non-aqueous impregnation and calcined at low temperature exhibited strong synergism in HDS activity. Co(Ni)Mo/MgO catalysts are much less deactivated by coking than their Al₂O₃-supported counterparts. Hydrodenitrogenation (HDN) activity of Mo/MgO catalyst is similar to the activity of Mo/Al₂O₃. However, the promotion effect of Co(Ni) in HDN on Co(Ni)Mo/MgO is lower than that on Co(Ni)Mo/Al₂O₃.     

Exafs study of the local structure of Ni in Ni-MoS2/C hydrodesulfurization catalysts

To study the local structure of the Ni promoter atom, the Ni and Mo K edge EXAFS spectra of Ni-MoS₂/C hydrodesulfurization catalyst were measured in an in-situ EXAFS cell at 77 K. The Ni atom is situated in a square pyramid of five S atoms at a distance of 2.21 Å from the S atoms. In addition an EXAFS contribution due to a Mo atom at 2.82 Å from the Ni atom could be identified. This local structure indicates that the Ni atoms are situated on top of the S₄ squares at the MoS₂ edges in millerite-type Ni sites. The Ni atoms are situated in the planes of the Mo atoms and not in the intercalation plane midway between successive MoS₂ sandwich layers.     

多孔ZSM-5沸石负载Ni2P催化剂对苯乙炔的选择性加氢性能

以酸性多孔ZSM-5沸石(HZSM-5-M)和高比表面积的氧化硅(SiO2)为载体，采用等体积浸渍法制备了负载Ni2P催化剂(Ni2P/HZSM-5-M和Ni2P/SiO2)，对比研究了它们在苯乙炔选择性加氢反应中的催化性能。采用XRD、N2吸附-脱附、NH3-TPD、H2-TPR、SEM和TEM对载体及其负载的Ni2P催化剂进行了表征。催化剂活性结果为：当反应时间为2 h，苯乙炔在Ni2P/HZSM-5-M催化剂的转化率为98.5%，而在Ni2P/SiO2催化剂上仅为45.6%。说明Ni2P/HZSM-5-M催化剂的加氢活性显著高于Ni2P/SiO2催化剂。这是因为，与Ni2P/SiO2催化剂相比，在Ni2P/HZSM-5-M催化剂上形成了小颗粒的Ni2P活性相。同时，Ni2P/HZSM-5-M催化剂的活性具有良好的重复性。