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1.
Partial oxidative gasification of n-hexadecane (n-C16) and organosolv-lignin (lignin) was studied by use of a batch type reactor in supercritical water: 673 K, 0.52 cm−3 of water density (40 MPa of water pressure at 673 K), and 0.3 of O/C ratio for the n-C16 experiments; 673 K, 0.35 cm−3 of water density (30 MPa of water pressure at 673 K), and 1.0 of O/C ratio for the lignin experiments. The experiments without O2 were also conducted for lignin (lignin decomposition). For all the cases (n-C16 partial oxidation, lignin decomposition, lignin partial oxidation), NaOH or zirconia (ZrO2) was added in the system as catalysts. Through n-C16 studies, the catalytic effect of NaOH and ZrO2 on partial oxidation in supercritical water were examined. In the case of lignin partial oxidation, we studied the possibility of partial oxidation in supercritical water for gasification technique of wastes. The yield of H2 from n-C16 and lignin with zirconia was twice as same as that without catalyst at the same condition. The H2 yield with NaOH was 4 times higher than that without catalyst. Thus, a base catalyst has a positive effect on partial oxidation of n-C16 and lignin to produce H2. The catalytic effect of NaOH and ZrO2 was found to be enhancement of decomposition of intermediate (aldehyde and ketone) into CO, through n-C16 studies. In the case of lignin studies, the enhancement of decomposition of the carbonyl compounds by catalytic effect of NaOH and ZrO2 inhibit char formation and promotes CO and thus H2 formation. 相似文献
2.
Dae Hyun Kim Jong Woo Ryu Eun Hyung Choi Gyeong Taek Gong Hyunjoo Lee Byung Gwon Lee Dong Ju Moon 《Catalysis Today》2008,136(3-4):266
The reforming process of gasoline is an attractive technique for fuel processor or hydrogen station applications. We investigated catalytic autothermal reforming (ATR) of iso-octane and toluene over transition metal supported catalysts. The catalysts were prepared by an incipient wetness impregnation method and characterized by N2 physisorption, XRD, and TEM techniques before and after the reaction. Many of the tested catalysts displayed reasonably good activity towards the reforming reactions of iso-octane. Especially, Ni/Fe/MgO/Al2O3 catalyst showed more activity than the other catalysts tested in this study including commercial HT catalyst. Ni/Fe/MgO/Al2O3 catalyst showed good stability for 700 h in the ATR of iso-octane. No major change was observed in catalytic activity in ATR of iso-octane or in the structure of catalyst. Since iso-octane, toluene are surrogates of gasoline, Ni/Fe/MgO/Al2O3 catalyst can be considered as ATR catalyst for gasoline fuel processor and hydrogen station systems. 相似文献
3.
Kwang-Jae Woo 《Fuel Processing Technology》2010,91(4):434-439
The CO conversion and selectivity to C1+ and C11+ wax products over Co/Al2O3 as well as Ru/Co/Al2O3 Fischer-Tropsch (F-T)catalysts were investigated by varying reaction temperature (210-250 °C), system pressure (1.0-3.0 MPa), GHSV (1000-6000 L/kg/h), superficial gas velocity (1.7-13.6 cm/s) and slurry concentration (9.09-26.67 wt.%) in a slurry bubble column reactor (0.05 m diameter × 1.5 m height) to determine the optimum operating conditions. Squalane or paraffin wax was used as initial liquid media. The overall CO conversion increased with increasing reaction temperature, system pressure and catalyst concentration. However, the local maximum CO conversion was exhibited at GHSV of 1500-2000 L/kg/h and superficial gas velocity of 3.4-5.0 cm/s. The CO conversion in the case of Ru/Co/Al2O3 was much higher and stable than that in the case of Co/Al2O3. The selectivity to C11+ wax products increased slightly with increasing GHSV; on the other hand, it decreased with increasing reaction temperature, system pressure, and solid concentration in a slurry bubble column reactor. It could be concluded that the optimum operating conditions based on the yield of hydrocarbons and wax products were; UG = 6.8-10 cm/s, Cs = 15 wt.%, T = 220-230 °C, P = 2.0 MPa in a slurry bubble column reactor for F-T synthesis. 相似文献
4.
In this work, the microwave-assisted CO2 reforming of CH4 over mixtures of carbonaceous materials and an in-lab prepared Ni/Al2O3 was studied. Ni/Al2O3 is not heated by microwave radiation, and for this reason, microwave receptors, such as carbonaceous materials, must be mixed with this catalyst. In order to evaluate the role of the carbonaceous component of the blend, two different carbonaceous materials were used: an activated carbon, FY5, and a metallurgical coke, CQ. The carbonaceous component acted not only as microwave receptor but also as catalyst and, consequently, it influenced the catalytic activity of the mixture. FY5 + Ni/Al2O3 was found to be a better catalyst than CQ + Ni/Al2O3, since FY5 on its own showed a better catalytic activity than CQ. Ni/FY5, which consists of Ni impregnated directly onto the microwave receptor, was also evaluated as a catalyst. It was found that the catalytic activity of the mixture FY5 + Ni/Al2O3 was better than that of Ni/FY5. Finally, the influence of the heating device on the catalytic activity of FY5 + Ni/Al2O3 was studied. Conversions over FY5 + Ni/Al2O3 and microwave heating were found to be similar to conversions over Ni/Al2O3 and conventional heating. 相似文献
5.
《Catalysis communications》2007,8(3):359-365
Isosynthesis is referred to the reaction that selectively converts syn-gas (CO + H2) to i-C4 hydrocarbons. Sm2O3 catalysts were prepared using a sol–gel technique with changing preparing parameters and the structure and textural properties of the catalysts were characterized by N2 adsorption–desorption isotherm, XRD and TEM. The influences of preparation parameters on the physical properties and the catalytic performance of Sm2O3 in isosynthesis were studied. The results showed that the Sm2O3 catalysts had lower activity but higher iso-C4 selectivity in the CO hydrogenation, compared with ZrO2 catalysts. Different preparation parameters had effects on the catalytic performance of Sm2O3 in isosynthesis. The Sm2O3 catalysts prepared by alco-method with highest surface area had the highest activity for iso-C4 formation. 相似文献
6.
Isomerization of n-hexane and n-heptane was carried out over Cs2.5H0.5PW12O40 (denoted by Cs2.5) promoted by Pt which was introduced by either impregnation of H2PtCl6 or mechanical mixing of Pt/Al2O3 and over non-promoted Cs2.5H0.5PW12O40 in the presence of hydrogen at atmospheric pressure. The reaction temperature studied was relatively low (typically 453 and
423 K for n-hexane and n-heptane, respectively) and the hydrogen pressure was also rather low (standard conditions: feed = n-alkane 0.05 atm, H2 0.20 atm, N2 balance; W/F = 40 g h mol−1). Results were compared with those obtained under the same conditions for other Pt-promoted solid acids, where particular
attention was paid to the time courses of the reaction (initial vs. stationary performance). Both the activity and selectivity
of Cs2.5 at the initial stage (after 5 min) increased by the addition of the Pt component. Pressure dependencies of the rate
at the initial stage were approximately first and −0.5th orders in alkane and hydrogen, respectively. Most remarkable was
the suppression of the deactivation during the reaction in the presence of both Pt and hydrogen. For example, the mechanical
mixture of Pt/Al2O3 and Cs2.5 (abbreviated as Pt+Cs2.5) showed little deactivation and much improved selectivity; resulting in high stationary
conversion and selectivity; e.g., 98.4 and 92.1% selectivities for n-hexane and n-heptane at the conversions of 58.6 and 39.4%, respectively. Most of the results were well explained by a classical bifunctional
mechanism, although other mechanisms are not all excluded. As for the other solid acids, the initial activity of Pt-promoted
SO4/ZrO2 was high, but decreased rapidly. The deactivation was small with Pt-promoted H-ZSM-5, but the activity was low. The stationary
yields of isomerized products were higher for Pt-promoted beta zeolite and Al-pillared saponite (tested only for n-heptane), although higher reaction temperatures were necessary.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
7.
Several polyoxometalates: Na2HPM12O40, H3PM12O40, Na2HPM12O40, (VO)H[PM12O40] and (n-Bu4N)3[PM12O40] (M = Mo and W) as well as (n-Bu4N)3 + x[PW12−xVxO40] (x = 0–3) were synthesized and characterized. Benzothiophene, dibenzothiophene and 4,6-dimethyl-dibenzothiophene were used as model sulfur compounds in gas oil. The oxidation reaction was performed using different polyoxometalates as catalyst and H2O2/acetic acid. The experimental results show that the W-based polyoxometalate catalysts are more active than the Mo catalysts. The oxidation reactivity of the catalysts depends on the type of countercation: Na+ > H+ > (VO)+ > (n-Bu4N)+. In a series of (n-Bu4N)3 + x [PW12−xVxO40] (x = 0–3) the order of catalytic activity is V3 > V2 > V1 > V0. The reactivity order of the sulfur compounds is: dibenzothiophene > 4,6-dimethyldibenzo-thiophene > benzothiophene. The catalytic system in this work was used for the oxidation of gas oil combined with solvent extraction to remove sulfur content in gas oil. Under mild reaction condition, high sulfur removal up to 98% can be achieved with high oil recovery (90%). 相似文献
8.
A systematic study of the comparative performances of supported Pt, Pd, Ru and conventional CoMo/Al2O3, NiMo/Al2O3, NiW/Al2O3 catalysts as well as the effects of solvent, H2 pressure and temperature on the hydroprocessing activity of a representative model bio-oil compound (e.g., p-cresol) is presented. With water as solvent, Pt/C catalyst shows the highest activity and selectivity towards hydrocarbons (toluene and methylcyclohexane), followed by Pt/Al2O3, Pd and Ru catalysts. Calculations indicate that the reactions in aqueous phase are hindered by mass-transfer limitations at the investigated conditions. In contrast, with supercritical n-heptane as solvent at identical pressure and temperature, the reactant and H2 are completely miscible and calculations indicate that mass-transfer limitations are eliminated. All the noble metal catalysts (Pt, Pd and Ru) show nearly total conversion but low selectivity to toluene in supercritical n-heptane. Further, conventional CoMo/Al2O3, NiMo/Al2O3 and NiW/Al2O3 catalysts do not show any hydrodeoxygenation activity in water, but in supercritical n-heptane, CoMo/Al2O3 shows the highest activity among the tested conventional catalysts with 97?% selectivity to toluene. Systematic parametric investigations with Pt/C and Pt/Al2O3 catalysts indicate that with water as the solvent, the reaction occurs in a liquid phase with low H2 availability (i.e., low H2 surface coverage) and toluene formation is favored. In supercritical n-heptane with high H2 availability (i.e., high H2 surface coverage), the ring hydrogenation pathway is favored leading to the high selectivity to 4-methylcyclohexanol. In addition to differences in H2 surface coverage, the starkly different selectivities between the two solvents may also be due to the influence of solvent polarity on p-cresol adsorption characteristics. 相似文献
9.
V. Matsouka M. Konsolakis R.M. Lambert I.V. Yentekakis 《Applied catalysis. B, Environmental》2008,84(3-4):715-722
The nature and relative populations of adsorbed species formed on the surface of un-promoted and sodium-promoted Pt catalysts supported either on bare Al2O3 or CeO2/La2O3-modified Al2O3, were investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) under simulated automobile exhaust conditions (CO + NO + C3H6 + O2) at the stoichiometric point. The DRIFT spectra indicate that interaction of the reaction mixture with the Pt/Al2O3 catalyst leads mainly to formation of formates and acetates on the support and carbonyl species on partially positively charged Pt atoms (Ptδ+). Although enrichment of Al2O3 with lanthanide elements (CeO2 and La2O3) does not significantly modify the carboxylate species formed on the support, it causes significant modification of the oxidation state of Pt, as indicated by the appearance of a substantial population of carbonyl species on reduced Pt sites (Pt0–CO). This modification of the Pt component is enhanced when Na-promotion is used, leading to formation of carbonyl species only on electron enriched Pt (i.e., fully reduced Pt0 sites) and to the formation of NCO on these Pt entities (2180 cm−1). The latter are thought to result from enhanced NO dissociation at Na-modified Pt sites. These results correlate well with observed differences in the catalytic performance of the three different systems. 相似文献
10.
Qing Yu Manfred Richter Landong Li Fanxiao Kong Guangjun Wu Naijia Guan 《Catalysis communications》2010,11(11):955-959
Selective catalytic reduction of NO by hydrogen was studied over Cr modified Pt/ZSM-35 catalysts. The preparation process greatly influenced catalytic activity and sample prepared by co-impregnation method exhibits the best activity. In situ DRIFT studies revealed that on Pt–Cr/ZSM-35, (1) new Pt-NOδ+ and NO species adsorbed on Pt were detected upon NO + O2 adsorption; (2) much more ammonia species were formed under reaction condition. Cr addition not only enhanced the adsorption of NOx but also promoted the formation of surface NH4+ species, which should be the origin of promotional effect of Cr on Pt/ZSM-35 for H2-SCR reaction. 相似文献
11.
Accelerated deactivation of 15 wt.% Co/Al2O3 catalyst in Fischer–Tropsch synthesis (FTS) in a single-bed and a dual-bed reactor is reported. Water was found to have a remarkable effect on the deactivation of Co/Al2O3 catalyst during FTS. Synthesis at higher temperatures and lower space velocities resulted in higher values of PH2O/(PCO + PH2) and PH2O/PCO and higher catalyst deactivation rates. Water-induced back-oxidation of cobalt, cobalt–alumina interactions, irreducible cobalt aluminates formation and refractory coke formation are the main sources of deactivation. When the water to carbon monoxide plus hydrogen ratio PH2O/(PCO + PH2) is greater than about 0.55 or water to carbon monoxide ratio PH2O/PCO is greater than about 1.5, it is not uncommon to find rapid catalyst deactivation. Separation of water and heavy hydrocarbons between the two catalytic beds of the dual-bed reactor, resulted in 62% lower catalyst deactivation rate than that of the single-bed reactor. The amount of refractory coke formation on the catalysts of the dual-bed reactor is 34% lower than that of the single-bed reactor. It was revealed that activity recovery of the used catalysts of the dual-bed is higher than that of the single-bed reactor. 相似文献
12.
Churchill T. Ako Alfred A. Susu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1986,36(11):519-526
The dehydrocyclisation of n-octane to iso-octane, ethylbenzene and o-, m- and p-xylene was investigated on monofunctional (non-acidic) and bifunctional (acidic) Pt/Al2O3 catalyst in a microcatalytic reactor with hydrogen as carrier at 1.8 atm and 563–673 K. On bifunctional Pt/Al2O3, the total conversion of n-octane started from a high value and decreased with increasing temperature for all pulse sizes investigated. The primary product of n-octane conversion on acidic Pt/Al2O3 was iso-octane. The product yield-temperature profiles showed a large initial production of iso-octane which decreased to a minimum as the catalyst temperature increased due to its conversion to ethylbenzene and o-xylene. On non-acidic Pt/Al2O3, the total conversion of n-octane increased initially and then went through a maximum as the catalyst temperature increased. The primary products of the reaction were found to be ethylbenzene and o-xylene, indicative of the activity of the metal to effect these ring closure reactions. 相似文献
13.
M. Zawadzki W. Walerczyk F.E. López-Suárez M.J. Illán-Gómez A. Bueno-López 《Catalysis communications》2011,12(13):1238-1241
Mesoporous and nanosized cobalt aluminate spinel with high specific surface area was prepared using microwave assisted glycothermal method and used as soot combustion catalyst in a NOx + O2 stream. For comparison, zinc aluminate spinel and alumina supported platinum catalysts were prepared and tested. All samples were characterised using XRD, (HR)TEM, N2 adsorption–desorption measurements. The CoAl2O4 spinel was able to oxidise soot as fast as the reference Pt/Al2O3 catalyst. Its catalytic activity can be attributed to a high NOx chemisorption on the surface of this spinel, which leads to the fast oxidation of NO to NO2. 相似文献
14.
Electro-catalytic oxidation of CO on Pt catalyst supported on carbon nanotubes pretreated with oxidative acids 总被引:2,自引:0,他引:2
Characteristics of nanosized Pt electro-catalyst deposited on carbon nanotubes (CNTs) were studied with CO-stripping voltammogram and chronoamperometry measurements. The CNTs were pretreated by oxidation in HNO3, mixed HNO3 + H2SO4 and H2SO4 + K2Cr2O7 solution, respectively, to enable surface modification. Well-homogenized Pt particles (average size: ≈3 nm) were loaded onto the pretreated CNT samples by a modified colloidal method. TEM, BET, FTIR and XRD techniques were used to characterize the physicochemical properties of the pretreated CNT samples. In the electro-oxidation of CO, all the Pt/CNT samples showed lower on-set as well as peak potentials than the conventional Pt/XC-72 electro-catalyst, indicating that the Pt/CNT samples were more resistant to CO poisoning and could be superior anode electro-catalyst for the proton exchange membrane fuel cells (PEMFCs). Moreover, we found that the pretreatment of CNTs in mixed HNO3 + H2SO4 solution was very beneficial for the performance enhancement of Pt/CNT electro-catalyst; the catalyst obtained as such gave the lowest peak potential and the highest catalytic activity for the electro-oxidation of CO. Larger amount of oxygen-containing functional groups, higher percentage of mesopores, and higher graphitic crystallinity of the pretreated CNTs were considered crucial for the performance enhancement, e.g., by strengthening the interaction between Pt nanoparticles and the CNT support and enhancing the mass diffusion in the electro-chemical reaction. 相似文献
15.
Pure and mixed gas n-C4H10 and CH4 sorption and dilation in poly(1-trimethylsilyl-1-propyne) (PTMSP) are reported at temperatures ranging from −20 to 35 °C. The presence of n-C4H10 in the mixture considerably reduces CH4 solubility. For example, CH4 solubility (in the limit of zero CH4 fugacity) at 25°C decreases from 4.0 (pure gas) to 0.78 cm3(STP)/(cm3 polymer atm) in the presence of n-C4H10 at an activity of 0.60. At −20 °C, CH4 solubility decreases by almost an order of magnitude, from 10.2 (pure gas) to 1.22 cm3(STP)/(cm3 polymer atm) in the presence of n-C4H10 at an activity of 0.61. In contrast, n-C4H10 mixture sorption properties are not measurably affected by the presence of CH4. The dual mode sorption model parameters for CH4 and n-C4H10 in PTMSP were determined from pure and mixed gas sorption measurements, and this model can adequately describe the sorption data. The n-C4H10/CH4 mixed gas solubility selectivity in PTMSP decreases as temperature increases and as n-C4H10 activity increases. For example, at 25 °C, the n-C4H10/CH4 solubility selectivity decreases from 250 to 120 as n-C4H10 activity increases from 0.02 to 0.25. At −20 °C and an n-C4H10 activity of 0.24, the n-C4H10/CH4 solubility selectivity is 590. Penetrant-induced volume dilation of PTMSP can be adequately modeled by assuming that all swelling is caused by penetrant molecules sorbed in the polymer's dense equilibrium region (i.e., the Henry's law region) during sorption. However, the best fit partial molar volumes in the Henry's law region for the dilation data are considerably lower than the penetrant partial molar volumes in liquids, suggesting that further theoretical efforts are needed to develop predictive models of volume dilation in high free volume glassy polymers. 相似文献
16.
E. A. Belopukhov I. M. Kalashnikov M. D. Smolikov D. I. Kir’yanov T. I. Gulyaeva A. S. Belyi 《Catalysis in Industry》2017,9(1):48-53
Pt/BEA–Al2O3 catalysts for the hydroisomerization of benzene-containing gasoline fractions are studied using a model feedstock (20% benzene and 80% n-heptane). The catalysts are prepared by varying the zeolite content from 5 to 70 wt % at a constant Pt loading of 0.3 wt % in all samples, with an aqueous H2PtCl6 solution being used as the Pt precursor. The acid properties of the samples are studied by means of temperature-programmed desorption (TPD). The effect of the support’s zeolite/binder ratio on the activity of the catalysts is determined: an increase in the zeolite content raises the system’s acidity and shifts the range of the reaction toward lower temperatures. The optimum zeolite/binder ratio is found to be 30% BEA/70% Al2O3. Changing the SiO2/Al2O3 ratio of the zeolite from 25 to 40 is shown to have no noticeable effect on catalyst activity. The use of the catalysts supported on 30% BEA/70% Al2O3 in the hydroisomerization of benzenecontaining gasoline fractions can be recommended for improving environmental performance. 相似文献
17.
M. D. Smolikov V. B. Goncharov E. M. Sadovskaya K. V. Kazantsev E. V. Zatolokina D. I. Kir’yanov E. A. Paukshtis B. S. Bal’zhinimaev A. S. Belyi 《Catalysis in Industry》2014,6(2):134-142
Samples of SO4/ZrO2/Al2O3 and Pt/Al2O3 Pt/Al2O3 catalysts and their physical mixtures are prepared, and the catalytic properties of the samples in n-hexane isomerization are studied. The considerable effect of the state of platinum on the catalytic performance of the samples is revealed. IR spectroscopy (COads), oxygen chemisorption, and oxygen-hydrogen titration show that the reduced catalysts contain ionic forms of platinum capable of adsorbing up to three hydrogen atoms per each surface atom of platinum. By means of H/D isotopic exchange, it is found that specific properties of ionic platinum are apparent in the formation of the hydride form of adsorbed hydrogen. It is speculated that the activity and stability of catalysts based on sulfated zirconia in n-hexane isomerization can be attributed to the involvement of ionic and metallic platinum in the activation of hydrogen. The results can be used to develop effective catalysts for the isomerization of C5–C6 gasoline fractions in order to obtain the isomerizate as a high-octane additive for modern gasolines. 相似文献
18.
N.V. Parizotto D. Zanchet K.O. Rocha C.M.P. Marques J.M.C. Bueno 《Applied Catalysis A: General》2009,366(1):122-129
The effects of Pt trace addition on the oxi-reduction properties of the Ni/Al2O3 and Ni/La–Al2O3 catalysts during partial oxidation of methane (POM) and autothermal reforming of methane (ATR) were investigated. The xPt–Ni/yLa–Al2O3 catalysts containing 15 wt% of Ni, 0 or 12 wt% of La and 0 or 0.05 wt% of Pt were characterized by temperature-resolved X-ray absorption near edge structure (XANES) spectroscopy under various atmospheres.The in situ XANES analysis for Pt–Ni/Al2O3 under H2 and CO revealed that the presence of Pt sites can initiate the NiO reduction process by rapid dissociation of H2 and migration of atomic H to the NiO surface by hydrogen spillover. On the other hand, in situ XANES analysis under CH4 showed that the presence of Pt sites induces the activation of the methane, probably by initial dissociation of methane (CH4 → CH3 + H) followed by migration of atomic H to the NiO surface. In situ XANES experiments under a POM mixture demonstrate that Pt has an important role keeping Ni in the metallic state. The catalytic test results for POM and ATR demonstrate that Pt is an important promoter to maintain Ni in the metallic state at the inlet region of the catalytic bed, where CH4 and O2 coexist. 相似文献
19.
Ni/Al2O3 with the doping of CeO2 was found to have useful activity to reform ethane and propane with steam under Solid Oxide Fuel Cells (SOFCs) conditions, 700-900 °C. CeO2-doped Ni/Al2O3 with 14% ceria doping content showed the best reforming activity among those with the ceria content between 0 and 20%. The amount of carbon formation decreased with increasing Ce content. However, Ni was easily oxidized when more than 16% of ceria was doped. Compared to conventional Ni/Al2O3, 14%CeO2-doped Ni/Al2O3 provides significantly higher reforming reactivity and resistance toward carbon deposition. These enhancements are mainly due to the influence of the redox properties of doped ceria. Regarding the temperature programmed reduction experiments (TPR-1), the redox properties and the oxygen storage capacity (OSC) for the catalysts increased with increasing Ce doping content. In addition, it was also proven in the present work that the redox of these catalysts are reversible, according to the temperature programmed oxidation (TPO) and the second time temperature programmed reduction (TPR-2) results.During the reforming process, in addition to the reactions on Ni surface, the gas-solid reactions between the gaseous components presented in the system (C2H6, C3H8, C2H4, CH4, CO2, CO, H2O, and H2) and the lattice oxygen (Ox) on ceria surface also take place. The reactions of adsorbed surface hydrocarbons with the lattice oxygen (Ox) on ceria surface (CnHm+Ox→nCO+m/2(H2)+Ox−n) can prevent the formation of carbon species on Ni surface from hydrocarbons decomposition reaction (CnHm⇔nC+m/2H2). Moreover, the formation of carbon via Boudard reaction (2CO⇔CO2+C) is also reduced by the gas-solid reaction of carbon monoxide (produced from steam reforming) with the lattice oxygen (CO+Ox⇔CO2+Ox−1). 相似文献
20.
Li[Co1−zAlz]O2 (0 ≤ z ≤ 0.5) samples were prepared by co-precipitation and solid-state methods. The lattice constants varied smoothly with z for the co-precipitated samples but deviated for the solid-state samples above z = 0.2. The solid-state method may not produce materials with a uniform cation distribution when the aluminum content is large or when the duration of heating is too brief. Non-stoichiometric Lix[Co0.9Al0.1]O2 samples were synthesized by the co-precipitation method at various nominal compositions x = Li/(Co + Al) = 0.95, 1.0, 1.1, 1.2, 1.3. XRD patterns of the Lix[Co0.9Al0.1]O2 samples suggest the solid solution limit is between Li/(Co + Al) = 1.1 and 1.2. Electrochemical studies of the Li[Co1−zAlz]O2 samples were used to measure the rate of capacity reduction with Al content, found to be about −250 ± 30 (mAh/g)/(z = 1). Literature work on Li[Ni1/3Mn1/3Co1/3−zAlz]O2, Li[Ni1−zAlz]O2 and Li[Mn2−yAly]O4 demonstrates the same rate of capacity reduction with Al/(Al + M) ratio. These studies serve as baseline characterization of samples to be used to determine the impact of Al content on the thermal stability of delithiated Li[Co1−zAlz]O2 in electrolyte. 相似文献