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1.
以喹啉为含氮模型化合物,在高压滴流床反应装置中考察了工业NiW/Al2O3催化剂RN-10上的加氢脱氮动力学规律,研究了反应温度330~420℃、氢分压1.2~5.2MPa、氢油比200~800(v/v)、重量空速(WHSV)20~70 h-1等反应条件对喹啉的加氢脱氮反应结果的影响.结果表明,反应温度对喹啉的脱氮率影响较大,提高反应温度可有效提高喹啉的脱氮率;同时,氢分压也是喹啉加氢脱氮的一个重要的影响因素,但是,当氢分压和氢油比较大时,氢分压和氢油比的变化对喹啉的脱氮率基本无影响.采用修正的n(n<1)级反应动力学模型对实验数据进行拟合,求得了喹啉加氢脱氮反应的表观活化能为180.4 kJ·mol-1.经检验,模型计算结果与实验结果能较好地吻合. 相似文献
2.
The activity of exfoliated MoS 2 in the hydrodesulfurization (HDS) of dibenzothiophene, the hydrodenitrogenation (HDN) of carbazole and the hydrogenation
of naphthalene has been determined. The catalytic activity was compared to MoS 2 prepared by the decomposition of molybdenum naphthenate (MoNaph). Exfoliated MoS 2 was found to give better overall HDS activity compared to MoNaph derived MoS 2 catalyst, whereas MoNaph derived MoS 2 was found to give higher hydrogenation and HDN activity. These results are discussed in terms of the morphology of the two
catalysts. The relative activity of the two catalysts in the hydrotreating reactions is shown to be different to that obtained
during Cold Lake bitumen hydrocracking. 相似文献
3.
本文通过多种测试技术研究了工业Co -Mo -K Al2 O3 耐硫变换催化剂 ,失活样中各元素的存在状态、含量和物相变化。发现 ,在原催化剂中钾、硫从内部向表面迁移并有流失 ,γ -Al2 O3 转变为 (Al2 O3 ) 10R ,MoS2 、Co9S8变为含活性硫物种少的物相 ;从反应气中夹带的铁、铬、硅和镍杂质沉积在表面上。由此导致催化剂对H2 O和CO的吸附与反应能力的下降 ,最终造成严重失活。 相似文献
4.
Co–Mo/ γ-Al 2O 3 oxide containing 9.8 wt% Mo and 2.9 wt% Co was prepared by high-intensity ultrasonic irradiation of Mo(CO) 6, Co 2(CO) 8, and γ-Al 2O 3 in decahydronapthalene under air flow. The oxidic Co–Mo catalyst thus formed was characterized by elemental analysis, BET
N 2 adsorption and XRD. The surface sites on the sulfided Co–Mo/ γ-Al 2O 3 catalyst were characterized by infrared spectroscopy of CO adsorption. Hydrodenitrogenation (HDN) and hydrodesulfurization
(HDS) activities were evaluated for heavy gas oil derived from Athabasca bitumen in a trickle bed reaction system using the
following conditions: temperatures ranging from 370 to 400 °C, a pressure of 8.8 MPa, a liquid hourly space velocity of 1 h −1, and a H 2/feed ratio of 600 ml/ml. The dispersion, nature of active sites and hydrotreating activity of this catalyst were compared
with the conventionally prepared Co–Mo/ γ-Al 2O 3 catalyst containing similar wt% of Mo and Co. The Co–Mo catalyst prepared by sonochemical method has higher HDN and HDS rate
constants than the conventional catalyst due to an improved dispersion of MoS 2. 相似文献
5.
With a small amount of H 2 (3 6%) addition into methane feed, coke formation on 6 wt% Mo catalyst during the methane dehydroaromatization reaction was effectively suppressed and the catalyst stability was increased evidently under the reaction conditions of 1023K, 0.3MPa and 2520 mL g-MFI -1 h -1 of methane space velocity. 相似文献
6.
The catalytic dehydro-aromatization reaction over Mo/HZSM-5 catalyst was drastically stabilized by the co-addition of 5.4%
H 2 and 1.8% H 2O to methane feed at 750 °C, 0.3 MPa and methane space velocity of 3000 mL g −1 h −1, suppressing the coke formation effectively, compared with single hydrogen or steam addition. 相似文献
7.
The effects of CO 2, CO and H 2 co-reactants on CH 4 pyrolysis reactions catalyzed by Mo/H-ZSM-5 were investigated as a function of reaction temperatures and co-reactant and CH 4 concentrations. Total CH 4 conversion rates were not affected by CO 2 co-reactants, except at high CO 2 pressures, which led to the oxidation of the active MoC
x
species, but CH
x
intermediates formed in rate-determining C–H bond activation steps increasingly formed CO instead of hydrocarbons as CO 2 concentrations increased. CO formation rates increased with increasing CO 2 partial pressure; all entering CO 2 molecules reacted with CH 4 within the catalyst bed to form two CO molecules at 950-1033 K. In contrast, hydrocarbon formation rates decreased linearly with increasing CO 2 partial pressure and reached undetectable levels at CO 2/CH 4 ratios above 0.075 at 950 K. CO formation continued for a short period of time at these CO 2/CH 4 molar ratios, but then all catalytic activity ceased, apparently as a result of the conversion of active carbide structures to MoO
x
. The removal of CO 2 from the CH 4 stream led to gradual catalyst reactivation via reduction-carburization processes similar to those observed during the initial activation of MoO
x
/H-ZSM-5 precursors in CH 4. The CO 2/CH 4 molar ratios required to inhibit hydrocarbon synthesis were independent of CH 4 pressure because of the first-order kinetic dependencies of both CH 4 and CO 2 activation steps. These ratios increased from 0.075 to 0.143 as reaction temperatures increased from 950 to 1033 K. This temperature dependence reflects higher activation energies for reductant (CH 4) than for oxidant (CO 2) activation, leading to catalyst oxidation at higher relative oxidant concentrations as temperature increases. The scavenging of CH
x
intermediates by CO 2-derived species leads also to lower chain growth probabilities and to a significant inhibition of catalyst deactivation via oligomerization pathways responsible for the formation of highly unsaturated unreactive deposits. CO co-reactants did not influence the rate or selectivity of CH 4 pyrolysis reactions on Mo/H-ZSM-5; therefore, CO formed during reactions of CO 2/CH 4 mixtures are not responsible for the observed effects of CO 2 on reaction rates and selectivities, or in catalyst deactivation rates during CH 4 reactions. H 2 addition studies showed that H 2 formed during CH 4/CO 2 reactions near the bed inlet led to inhibited catalyst deactivation in downstream catalyst regions, even after CO 2 co-reactants were depleted. 相似文献
8.
Catalytic activity of a 1 wt% Au/TiO 2 catalyst is markedly improved by loading a large amount of FeO x, on which the oxidation of CO in excess H 2 is selectively promoted at temperature lower than 60 °C. Oxidation of CO with O 2 on the FeO x/Au/TiO 2 catalyst is markedly enhanced by H 2, and H 2O moisture also enhances the oxidation of CO but its effect is not so large as the promotion by H 2. We deduced that activation of Au/TiO 2 catalyst by loading FeO x is not caused by the size effect of Au particles but a new reaction path via hydroxyl carbonyl intermediate is responsible
for the superior activity of the FeO x/Au/TiO 2 catalyst. 相似文献
9.
A novel process was developed for the bitumen emulsion upgrading, wherein emulsion breaking and upgrading occurred in the same reactor using H 2 generated in situ from the water in the emulsion via the water gas shift reaction (WGSR). In this study, dibenzothiophene (DBT) was chosen as a model compound to investigate the effect of water and in situ H 2 on hydrodesulfurization (HDS). All the experiments were performed in a 1-L autoclave reactor at temperatures between 300 and 380 °C using in situ H 2 and ex situ H 2 (externally supplied H 2) over a dispersed Mo catalyst formed from phosphomolybdic acid (PMA). At very low water content, water was found to promote the HDS reaction in the ex situ H 2 run probably because it facilitates the formation of more active dispersed MoS x species. At higher water content, however, water inhibits every individual reaction in the reaction network in the HDS of DBT, blocking the hydrogenation pathway more than the hydrogenolysis pathway. The relative reactivity of the in situ and ex situ H 2 depends on the water content present in the reaction system. At an optimized mole ratio of H 2O:CO (1.35), higher HDS activity was observed in the in situ H 2 run compared to ex situ H 2 run, and particularly, the hydrogenation pathway was promoted in the in situ H 2 run. 相似文献
10.
The spectroscopy and kinetics of a new low-temperature methanol synthesis method were studied by using in situ DRIFTS on Cu/ZnO catalysts from syngas (CO/CO 2/H 2) using alcohol promoters. The adsorbed formate species easily reacted with ethanol or 2-propanol at 443 K and atmospheric
pressure, and the reaction rate with 2-propanol was faster than that with ethanol. Alkyl formate was easily reduced to form
methanol at 443 K and 1.0 MPa, and the hydrogenation rate of 2-propyl formate was found to be faster than that of ethyl formate.
2-Propanol used as promoter exhibited a higher activity than ethanol in the reaction of the low-temperature methanol synthesis. 相似文献
11.
The effects of the pretreatments of Cu/ZnO-based catalysts prepared by a coprecipitation method on their activities for the water–gas shift reaction at 523K were investigated. The activity of a Cu/ZnO/ZrO 2/Al 2O 3 catalyst for the water–gas shift reaction was less affected by calcination at temperatures ranging from 673-973K and by H 2 treatment at 573 or 723K than that of a Cu/ZnO/Al 2O 3 catalyst. The catalyst activity could be correlated mainly to the Cu surface area of the catalyst. 相似文献
12.
A comparative study of the syntheses of unsupported WS 2 and M/WS 2 (M = Co, Ni) catalysts by ex situ/in situ decomposition of ammonium thiotungstate (ATT) is herein reported. Ex situ activation was performed under a H 2S (15% volume)/H 2 flow, whereas in situ activation consists in the direct decomposition of ATT or Co(Ni)/ATT precursors in the presence of a hydrocarbon solvent during the hydrodesulfurization (HDS) of dibenzothiophene (DBT). Precursors were characterized by thermogravimetric analysis and final catalysts by X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area (BET). Catalysts activated using the in situ mode of activation present higher specific surface areas with the noticeable exception of the Ni/ATT precursor. Activity measurements showed that the in situ activated WS 2 and Ni/WS 2 catalysts exhibit higher activity than the ex situ activated catalysts. 相似文献
13.
ABSTRACTDouble mixed Cu 0.5Co 0.5Fe 2O 4 ferrite nanoparticles were found as a highly efficient and magnetically separable nanocatalyst for the synthesis of varied flavanone antioxidants. A wide range of flavanone derivatives were prepared with excellent isolated yields within the short reaction times. The catalyst could be separated using a simple magnetic extraction and reused 6 times with no remarkable loss of activity. The high activity of the prepared catalyst was attributed to the cooperative activation of the carbonyl group by both copper and cobalt via a synergistic catalytic effect that facilitates the Micheal addition of the hydroxyl group to the α,β-unsaturated ketone. 相似文献
14.
Oxidation of CO on the FeO
x
/Pt/TiO 2 catalyst is markedly enhanced by H 2 and/or H 2O at 60 °C, but no such enhancement is observed on the Pt/TiO 2 catalyst, but shift reaction (CO + H 2O → H 2 + CO 2) does not occur on the FeO
x
/Pt/TiO 2 catalyst at 60 °C. DRIFT-IR spectroscopy reveals that the fraction of bridge bonded CO increases while that of linearly bonded
CO decreases on the FeO
x
loaded Pt/TiO 2 catalyst. The in-situ DRIFT IR spectra proved that the bridged CO is more reactive than the linearly bonded CO with respect to O 2, and the reaction of the bridge-bonded CO with O 2 as well as of the linearly bonded CO is markedly enhanced by adding H 2 to a flow of CO + O 2. From these results, we deduced that the promoting effect of H 2 and/or H 2O is responsible for the preferential oxidation (PROX) reaction of CO on the FeO
x
/Pt/TiO 2 catalyst, and a following new mechanism via the hydroxyl carbonyl or bicarbonate intermediate is proposed for the oxidation
of CO in the presence of H 2O.
相似文献
15.
A new way was provided for in situ synthesized FCC catalyst. Characterization and evaluation results indicated the catalyst is more suitable for cracking resid
feed because of its unique manufacturing process which makes this catalyst has appropriate pore structures in which large
resid molecules are more accessible to the active sites. The high zeolite content (above 40%) keeps the catalyst having higher
activity and selectivity. These advantages ensure the in situ catalyst developed more adaptable for cracking resid and resid-containing feedstocks, particularly the feed containing large
amounts of contaminant metals. 相似文献
16.
A series of transition metal oxides promoted titania catalysts (MO
x
/TiO 2; M = Cr, Mn, Fe, Ni, Cu) were prepared by wet impregnation method using dilute solutions of metal nitrate precursors. The
catalytic activity of these materials was evaluated for the selective catalytic reduction (SCR) of NO with CO as reductant
in the presence of excess oxygen (2 vol.%). Among various promoted oxides, the MnO
x
/TiO 2 system showed very promising catalytic activity for NO + CO reaction, giving higher than 90% NO conversion over a wide temperature
window and at high space velocity (GHSV) of 50,000 h −1. It is remarkable to note that the catalytic activity increased with oxygen, up to 4 vol.%, under these conditions leading
primarily to nitrogen. Our TPR studies revealed the presence of mixed oxidation states of manganese on the catalyst surface.
Characterization results indicated that the surface manganese oxide phase and the redox properties of the catalyst play an
important role in final catalytic activity. 相似文献
17.
The photocatalytic reduction of CO 2 with H 2O to produce CH 4 and CH 3OH was found to proceed in the gas phase at 323 K with different reactivities and selectivities on hydrophilic Ti-Beta(OH) and hydrophobic Ti-Beta(F) zeolites prepared in the OH – and F – media, respectively. In situ XAFS measurements have revealed that these differences are attributed to the differences in the affinity for the adsorption of H 2O molecules on the highly dispersed tetrahedrally coordinated titanium oxide species depending on the hydrophobic–hydrophilic properties of zeolites. 相似文献
18.
A conventional NO
x
-trap catalyst containing platinum, rhodium, barium and lanthanum was conditioned with oxygen at 500°C, preloaded with NO under standard oxidising conditions and then subjected to regeneration with the reductants H 2, CO and C 3H 6, either alone or as a mixture. Hydrogen is the most efficient reductant in terms of NO
x
conversion efficiency and reductant usage efficiency. There is a temperature optimum for CO between 300 and 400°C and a catalyst loading optimum (mols reductant added)/(mols NO
x
adsorbed) between 1.5 and 3.0. The behaviour of the catalyst towards sulphur poisoning was examined in supplementary trials with the adsorption of SO 2 in the presence or absence of water vapour. When water is not present in both adsorption and reduction steps, very stable sulphates are formed, unattacked by reductants even at 1000°C. Sulfates are more easily reduced when water is present in the reductant mixture. 相似文献
19.
A concise and efficient method for the synthesis of 3,4,5-substituted furan-2 (5 H)-ones was achieved through a three-component reaction of amines, dialkyl acetylene dicarboxylate, and aromatic aldehydes using nano-CdZr 4(PO 4) 6 as catalyst under microwave irradiation. This method has several advantages such as, high efficiency, short reaction times, simple workup, and recyclability of the catalyst up to seven runs without considerable loss of activity. 相似文献
20.
The effect of deposition and order of potassium introduction on the texture and activity of Mo/γ-Al 2O 3 catalysts in water gas shift (WGS) reaction was investigated. The samples were synthesised by incipient wetness impregnation of the carrier with aqueous solutions of the corresponding salts followed by drying and calcination after each deposition step. The prepared catalyst precursors were sulphided at 400°C for 2 h with 6% H 2S in H 2 before testing in WGS reaction in a glass flow apparatus at 400°C under atmospheric pressure. The results show that potassium deposition alone on the bare γ-Al2O3 (sample K/Al2O3) decreases the specific surface after calcination by blocking the constrictions between the pores in the primary porous texture. In the WGS reaction conditions part of the pores are deblocked and a redistribution in the pore volumes occurs. The deposition of the Mo (sample Mo/Al2O3) also results in a decrease in both specific surface and total pore volume with respect to the bare support. However after catalytic activity test no substantial changes in its texture were observed. The addition of K to the Mo (sample KMo/Al2O3) leads to nonuniformity in distribution of molybdenum–oxygen entities due to partial migration of the MoOx species to the external surface. The specific surface is not changed during the reaction test. The deposition of Mo on K/Al2O3 contributes to the uniform distribution of oxomolybdenum species in the porous texture of the support. This uniformity is preserved to a high extent in the catalytic reaction as well. The activity in the synthesised samples in the WGS reaction decreases in the order MoK/Al2O3 > Mo/Al2O3 > KMo/Al2O3. 相似文献
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