Effects of Metal-Support Interactions and Interfaces on Catalytic Performance over M 2 O 3 - ( M = La , Al-) Supported Ni Catalysts

. The metal-support interactions and their interfaces have showed great in ﬂ uence on catalytic activity and stability. Herein, di ﬀ erent support of M 2 O 3 - ( M = La , Al-) supported Ni catalysts was prepared by a citric acid-assisted sol-gel method. The physical structure and chemical properties of the As-prepared catalysts were systematically characterized by various technologies. The catalytic performance was evaluated for hydrogen or syngas production by ethanol steam reforming and methane dry (CO 2 ) reforming, respectively. The results showed that compared with Al 2 O 3 support, the nickel supported on La 2 O 3 possessed a smaller particle size of nickel even after high-temperature reduction. In addition, the La 2 O 3 -supported nickel catalyst had stronger metal-support interaction and higher nickel electron density as a result of higher ethanol conversion activity and stability. The ethanol conversion was maintained at 87.8% after a 3000-minute test, and the hydrogen production was as high as 6500 μ mol/min. Moreover, the Ni-La 2 O 3 catalyst also showed good activity for methane dry reforming. The initial conversion of methane and carbon dioxide was close to 90%, and the ratio of H 2 /CO reached 0.94. The better catalytic performance of the Ni-La 2 O 3 catalyst was ascribed to smaller particle size of Ni, rich metal-support interfaces, more nickel electron densities, abundant strong basic sites, and strong metal-support interactions.


Introduction
Nowadays, the hypersonic aircraft has become a hot spot in the field of aerospace development.However, it will generate a lot of pneumatic heat in flight, which may cause the surface temperature of aircraft higher than the material tolerance and will lead to decay of the life-span or even destroy the material [1].Therefore, controlling the surface temperature lower than the material tolerance is highly desirable for dealing with the problem of vehicle cooling with liquid hydrocarbon fuel [2].Due to the high temperature of hypersonic flight vehicle cooling requirements and the shortcomings of liquid hydrogen fuel such as low density and low boiling point, endothermic hydrocarbon fuel is a good way for response to problems of hypersonic flight vehicles [3].For endothermic hydrocarbon fuel process, three aspects including steam reforming, catalytic dehydrogenation, and cracking have been extensively investigated [4,5].Compared with the cracking or dehydrogenation process, fuel steam reforming process can provide a higher heat sink and can meet the actual requirements of hypersonic missiles with flight speed up to Mach 10 [3].Adding water/ethanol to fuel was based on a two-step reaction involving the lowtemperature prereforming of fuel to produce methane and carbon dioxide, and then the methane and carbon dioxide (dry) reforming under high-temperature conditions with strong endothermic effect [6].Therefore, fuel steam reforming such as ethanol steam reforming and methane carbon dioxide reforming is expected to provide a fundamental data for improving the heat absorption capacity of fuel.Furthermore, ethanol steam reforming and methane carbon dioxide reforming are important reactions for production of hydrogen and syngas, which have become one of the hot spots [7][8][9][10][11][12].
Whether ethanol steam reforming or methane carbon dioxide reforming, the key to achieve high conversion is the design high-efficiency catalysts [13,14].Among them, nickel-based catalysts were regarded as the most promising catalysts for reforming reactions because of the high activity, abundant resource, and low price [15].However, there are still some shortcomings for nickel-based catalysts, such as easy carbon deposition on the surface of nickel, which reduces the activity and stability of the catalysts [16].Moreover, due to the low Taman temperature of nickel metal, it tends to agglomerate under high-temperature reaction conditions, which further greatly reduces the activity and stability of the catalyst.Therefore, it is an urgent problem to improve the carbon deposition resistance and sintering resistance of nickel-based catalysts [17].Based on previous report, increasing the dispersion of nickel, reducing the particle size of nickel, and enhancing the interaction strength  between nickel metal and support are efficient methods to improve the activity and stability for nickel-based catalysts [18,19].Xiao et al. [20] reported that the Ni-CePr x catalyst prepared by the sol-gel method achieves stable hydrogen production by ethanol steam reforming.The catalyst prepared by the sol-gel method has higher activity and anticarbon deposition performance than the catalyst prepared by the impregnation method, which was attributed to the strong interaction between nickel metal and support and the high nickel dispersion.Further, they also reported that Ni-CeO 2 catalysts modified by valence states of different doping elements can achieve stable hydrogen production by ethanol steam reforming [21].In particular, the Ladoped catalyst has higher activity and stability, which was attributed to the greater nickel dispersion and oxygen vacancy concentration of the trivalent La-doped catalyst.La 2 O 3 and Al 2 O 3 were excellent support for supporting nickel catalysts, which have strong interaction with metal nickel and can form high-temperature sintering-resistant perovskite [22] or nickel-aluminum spinel structure [23].
Herein, La 2 O 3 -and Al 2 O 3 -supported nickel catalysts were synthesized by a sol-gel method.The structures and properties of the two catalysts were characterized by wideangle X-ray diffraction (XRD), nitrogen adsorption and desorption isotherm, transmission electron microscopy (TEM), CO 2 temperature-programmed desorption (CO 2 -TPD), X-ray photoelectron spectroscopy (XPS), and a hydrogen temperature-programmed reduction (H 2 -TPR).The results showed that the nickel catalysts supported on the two kinds of support have different performances for ethanol steam reforming and methane dry reforming.Furthermore, TEM and thermogravimetric analysis (TG) were performed on the spent catalyst.The La 2 O 3 -supported nickel catalyst showed better catalytic activity and stability as well as anticarbon deposition performance on account of its strong metal-support interaction, rich metal-support interaction interface, and smaller particle size of nickel.: N 2 = 1 : 1 : 2, Tianjin Taiya Gas Company), nitrogen (high purity), and helium (high purity) were purchased from Six Party Gas Company, deionized water.

Preparation of Catalyst.
The catalyst was prepared by a sol-gel method as reported by our previous work [24,25].For the synthesis of Ni-La 2 O 3 , a certain amount of lanthanum nitrate hexahydrate and nickel nitrate hexahydrate were weighed, then dissolved in 17 mL deionized water.Then, citric acid with molar ratio to metal ion set at 2 : 1 was added into the above solution.After stirring for 6 h, the above mixed solution was transferred into oven under 120 °C for 12 h.The obtained solid was ground to a powder and then transferred to a muffle furnace at 600 °C for 4 h.To prepare the reduced catalyst, a certain amount of calcined catalyst was put in a quartz ark and reduced at  3 International Journal of Energy Research catalyst was prepared by the same method, and the precursor of aluminum used was aluminum nitrate nonahydrate.

Characterization.
The phase structure of the prepared catalyst and the reduced catalyst was analyzed by the Rigaku D8 Focus X-ray diffractometer (XRD).The test conditions of XRD were as follows: Cu target, K α ray (λ = 0:154 nm), tube voltage of 40 kV, tube current of 200 mA, scanning speed set at 8 °/min, and scanning range from 10 °to 80 °.The instrument JEM-F200 was used to observe the nickel particles and carbon deposition of the prepared catalyst.At the same time, selected electron diffraction and crystal structure analysis could be provided, and the surface distribution analysis of the sample elements could be analyzed with the energy spectrometer.The test conditions were as follows: acceleration voltage of 200 kV, point resolution ≤ 0:19 nm, and STEM resolution ≤ 0:20 nm.Micromeritics Tristar 3000 was used to analyze the pore structure of the material under nitrogen atmosphere at -196 °C.The samples were needed to be degassed and dehydrated for 3 h at 300 °C before the test.H 2 -TPR was carried out on an AMI-300.Firstly, a certain amount of catalyst samples were weighed and pretreated at 400 °C in Ar atmosphere for 1 h.After cooling to 50 °C, 10% vol H 2 -Ar-mixed gas was added and the temperature was increased from 50 °C to 800 °C with the heating rate of 10 °C/min.CO 2 -TPD was carried out on an AMI-300.A powder sample (100 mg) was pretreated at 300 °C with Ar under a flow of 30 mL/min for 1 h and then cooled to °C for 20 minutes, and then the temperature was increased from 30 °C to 800 °C in the air atmosphere with a heating rate of 10 °C/min.The weight loss curve of the sample was obtained, and DTG data was obtained by first-order differentiation of the weight loss curve.

Catalyst Evaluation.
Hydrogen production by ethanol steam reforming was carried out in a stainless-steel tubular-fixed bed reactor.Before reaction, the calcined catalyst was pressed into tablets with the pressure of 10 MPa, and then was sieved into mesh number of 20~40.For ethanol steam reforming, 0.25 g of catalyst and 1.2 g of quartz sand were mixed uniformly and then filled in a stainless-steel tubular with a diameter of 6 mm.The temperature was raised to 780 °C in nitrogen, then the gas was switched to 10% vol H 2 /Ar.After reducing for 1 h, the temperature was stabilized to the reaction temperature (600 °C) by nitrogen, and the reaction pressure was set at 0.1 MPa.A constant quantity of ethanol aqueous solution (0.255 mL/min) was introduced into the gasifier by a high-pressure metering pump, then gasification at 300 °C with nitrogen (60 mL/ min).The partial pressure of ethanol vapor and nitrogen in the mixture were 15.73 vol% and 21.33 vol%, respectively.During the reaction, the gas hour space velocity (GHSV) of 5 International Journal of Energy Research ethanol-water vapor was 55920 mL/g cat •h.After the reaction, the gas product was condensed, dried, and passed through Micro GC 490 (Agilent) for online analysis.The gas chromatographic with a TCD detector was equipped with three columns: an activated alumina column for the detection of hydrocarbon molecules C 3 and above, a PPU column for the detection of CO 2 , ethane, and ethylene, and a 5 Å MS column for the detection of H 2 , N 2 , CH 4 , and CO.The conversion of ethanol was calculated according to Equation (1).The gas product rate and the composition of gas were calculated based on Equations ( 2) and (3).Similar to ethanol steam reforming, methane dry reforming was carried out in the same reactor.The 0.15 g of catalyst and 1.2 g of quartz sand were evenly mixed and loaded into a tube reactor, and then prereduced in 10% vol H 2 /Ar mixture at 780 °C for 1 h.The temperature was stabilized to 700 °C under a nitrogen atmosphere.Then the mixture of methane, carbon dioxide, and nitrogen gas with a ratio of 1 : 1 : 2 was passed into the reaction tube; and nitrogen was used as the carrier gas and internal standard gas.The gas phase products were analyzed by GC490, and the gas production rate, reactant conversion, and H 2 /CO molar ratio were calculated by using Equations ( 2), ( 4), and (6).F out CO , F out CO 2 , and F out CH 4 represent the total number of C 1 products at the outlet of the reaction tube (mol/min).For Equation (2), R ðN 2 Þ = 60 mL/min, namely, nitrogen flow rate, A H2 and f H2 represent the peak area Here, Equation (3), V% (H 2 ) (excluding nitrogen) was the percentage of hydrogen in the dry gas (without nitrogen).

Ethanol conversion rate
Gas production rate

Characterization of Structure and Metal-Support
Interaction.The XRD patterns of the As-reduced catalysts are shown in Figure 1(a).For the Ni-Al 2 O 3 catalyst, no obvious peak of Al 2 O 3 was observed, which could be due to its amorphous structure [19].The diffraction peaks with strong intensity appear at 44.5 o , 51.9 o , and 76.4 o were attributed to the characteristic diffraction peaks of nickel (JCPDF#01-1260), indicating that the high crystallinity of nickel in the reduced catalyst with the uneven distribution of large particles size of nickel.For the Ni-La 2 O 3 catalyst, the peaks of La 2 O 3 (JCPDF#83-1344) was mainly observed.There was no obvious characteristic peak of nickel, illustrating that the small particle size of nickel with uniform distribution.These results will be confirmed by H 2 -TPR as shown in Figure 1(b).All the As-prepared catalysts have three reduction peaks.For the Ni-Al 2 O 3 catalyst, the reduction peak of 391.1 °C was attributed to the reduction of NiO with large particles or weak interaction with the support, and 484.1 °C was assigned to the reduction of NiO with small particles or strong interaction with the support, and 695.4 °C was attributed to the reduction of nickel-aluminum spinel [19].For the Ni-La 2 O 3 catalyst, the first peak appeared at 416.9 °C, which can be attributed to the decrease of Ni 2+ species on the surface.The second peak appeared at 609.3 °C, possibly because LaNiO 3 was reduced to La 2 Ni 2 O 5 [26].The third reduction peak was located at 767.7 °C, which corresponds to the reduction of Ni 2+ in LaNiO 3 to metal Ni 0 [27].The higher reduction temperature of the Ni-La 2 O 3 catalyst indicates that it possessed a strong metal-support interaction, which is beneficial to inhibit the sintering of nickel and maintain the small particle size of nickel during the high-temperature reduction process.
The nitrogen adsorption-desorption isotherms of the calcined catalyst are shown in Figure 1(c) with hysteresis loop indicating that the prepared catalyst was a mesoporous material.With the increase of the relative pressure, the adsorption capacity also increases, indicating that there was a certain amount of large pores in the material.The pore size showed double pore size distribution.The mesoporous pore was centered at 4 nm and the macroporous was around 60 nm.From Table 1, the specific surface area of the Ni-Al 2 O 3 catalyst was 51.3 m 2 /g, the pore volume was 0.11 m 3 / g, and the average pore size was 7.8 nm (inset Figure 1(c)).For the Ni-La 2 O 3 catalyst, the surface area and pore volume were decreased to 23.3 m 2 /g and 0.04 m 3 /g, respectively.The results indicate that the prepared catalyst has a porous structure and its specific surface area was relatively small.
In order to illustrate the alkaline site on different supports, the data of CO 2 -TPD was collected as shown in Figure 1(d).For Ni-La 2 O 3 , the high intensity of CO 2 desorption peak was mainly centered on 782 °C, which illustrates abundant and strong basic sites, while for the Ni-Al 2 O 3 , the main CO 2 desorption temperature was located at 167 °C and 473 °C, which means weak and few basic sites.The strong basic sites for Ni-La 2 O 3 may play a positive influence on CO 2 adsorption during the methane dry reforming, thus exhibiting good activity and stability for methane dry reforming [17].[28] pointed out that the enhanced electron density of nickel enhances the activation and dissociation of CO 2 and balances the formation rates of C and O species on the catalyst.In addition, the Ni 0 / (Ni 0 + Ni 2+ ) ratio was also calculated.The Ni 0 ratios of Ni-La 2 O 3 and Ni-Al 2 O 3 were 59.9% and 56.9%, respectively, indicating that the ratio of nickel for two catalysts was similar.

TEM Analysis of Reduced Catalyst.
Apart from binding energy of Ni, the particle size of nickel is also play vital important role in catalytic performance.The TEM images of the reduced catalyst are shown in Figure 3.The distribution of nickel particles in the Ni-La 2 O 3 catalyst was relatively uniform, and the average particle size was 13.5 nm (inset Figure 3(a)).It was found that some nickel particles were embedded in the support and showed strong interaction with the support and more metal-support interfaces, which was consistent with the results of H 2 -TPR (Figure 1(b)).Moreover, according to HR-TEM, the lattice parameter of nickel particles was 0.201 nm, which corresponds to the Ni (111) crystal plane.The interaction interface between nickel particles and La 2 O 3 support was large (Figure 3(b)).For the Ni-Al 2 O 3 catalyst, agglomeration of nickel particles was observed and the average particle size was 45.2 nm (inset Figure 3(c)), indicating the contact interface between nickel particles and the support was small (Figure 3(d)).These results were consistent with the previous XRD and TPR results.According to literature, nickel particles have strong metal-support interaction, which makes them smaller 9 International Journal of Energy Research particle sizes and rich interaction interfaces, leading to the better catalytic activity and sintering resistance [23].
The element distribution of reduced Ni-La 2 O 3 and Ni-Al 2 O 3 catalyst are analyzed by the TEM-mapping technique.As shown in Figure 4(a), the high-angle dark field images showed that Ni nanoparticles were uniformly distributed on the La 2 O 3 support (Figures 4(b)-4(e)).However, for the Ni-Al 2 O 3 catalyst (Figures 5(a)-5(e)), the nickel particles were agglomerated, which was consistent with the previous TEM and XRD results.In high temperature (780 °C) hydrogen atmosphere, the nickel particles of Ni-La 2 O 3 catalysts remain uniformly dispersed, due to the strong metalsupport interaction which help to inhibit the agglomeration of Ni particles.
3.4.Catalytic Performance.The stability of ethanol steam reforming was studied at 600 °C, the molar ratio of H 2 O/ C 2 H 5 OH was 4 : 1, and the GHSV of aqueous ethanol vapor was 55920 mL/g cat •h, under atmospheric pressure, as shown in Figure 6.Ni-La 2 O 3 catalyst has higher ethanol steam reforming activity and stability than Ni-Al 2 O 3 (Figure 6(a)).For Ni-Al 2 O 3 , the conversion rate of ethanol decreased rapidly from 50.2% to 15.1% within 360 min, and the conversion decreased by nearly 70% (Figure 6(b)).Similarly, the hydrogen production rate decreased from 4529.9 μmol/min to 1659.3 μmol/min.The rapid deactivation of Ni-Al 2 O 3 in the steam reforming of ethanol may be related to weak metal-support interaction, which cause the serious metal sintering and carbon deposition.For Ni-La 2 O 3 , the conversion of ethanol increased to 93.9% and the hydrogen production rate was 6913.6 μmol/min after 75 min.After 3000 min, the conversion still remained at 87.8%, and the hydrogen production rate remained as high as 6579.4μmol/min.The ethanol conversion rate of the Ni-La 2 O 3 catalyst decreased by only 6.1%, which was much smaller than that of Ni-Al 2 O 3 .Meanwhile, the gas produc-tion composition (Figures 6(c) and 6(d)) were closed to balanced composition [20,21].
The high activity and stability of the Ni-La 2 O 3 catalyst can be attributed to its strong metal-support interaction, rich metal-support interface, abundant nickel electron density, and small particle size of nickel [20,21].The relative low decrease of the ethanol conversion of Ni-La 2 O 3 catalyst can be attributed to the enhancement of anticarbon deposition performance, which will be confirmed by the following XRD and TG results.Also, the catalyst performance was compared with these previous reported (Ref [29][30][31][32][33][34][35][36][37][38]) as summarized in Table 2.The Ni-La 2 O 3 catalyst designed in this study has higher ethanol steam reforming activity, greater stability, and good carbon deposition resistance and will be used in future.
Furthermore, our Ni-La 2 O 3 can be used to convert methane and carbon dioxide under harsh reaction condition as shown in Figure 7.Under the same reaction condition, Ni-La 2 O 3 catalyst showed higher activity and stability of methane dry gas reforming than that of Ni-Al 2 O 3 .The initial conversion rates of methane and carbon dioxide over Ni-La 2 O 3 catalyst were 92.6% and 92.5%, respectively (Figures 7(a) and 7(b)).While, the initial conversion rates of methane and carbon dioxide over Ni-Al 2 O 3 catalyst were 76.3% and 86.5%, respectively.After 140 min reaction, the conversion rates of methane and carbon dioxide were 84.4% and 82.2% for Ni-La 2 O 3 catalyst, which were higher than those of Ni-Al 2 O 3 catalyst.In addition, the H 2 /CO ratio of the Ni-La 2 O 3 catalyst remained at 0.94, while for the Ni-Al 2 O 3 catalyst decreased to 0.85 after 140 min of reaction (Figure 7(c)).The hydrogen production rate (Figure 7(d)) of the Ni-La 2 O 3 catalyst was maintained at 1.49 mmol/min, which was 1.37 times higher than that of the Ni-Al 2 O 3 catalyst (1.09 mmol/min).These results indicate that Ni-La 2 O 3 has higher catalytic activity and stability than Ni-Al 2 O 3 during the methane dry reforming.Ni-Al 2 O 3 after ethanol steam reforming reaction was 21.7%, indicating that the of carbon deposition in the catalyst after the reaction was 21.7%.For the spent Ni-La 2 O 3 catalyst, the weight loss rate was significantly reduced.The better anticarbon deposition performance of the Ni-La 2 O 3 catalyst is attributed to the smaller size of Ni particles, the abundant metal-support interface, and the abundant strong basic sites, which is beneficial to the inhibition of carbon deposition.
In addition, the differential thermal analysis of the catalyst after the reaction is shown in Figure 10(a).The temperature for oxidation of carbon on Ni-Al 2 O 3 catalyst was concentrated at 594.9 °C, which corresponds to the oxidation of the encapsulated carbon on the surface of nickel metal.For spent La 2 O 3 , the elimination temperature of carbon deposition on nickel surface moves to the low temperature (592 °C) zone and the peak area was greatly reduced.The main carbon deposition oxidation temperature was 761.8 °C, which was attributed to the oxidation of carbon nanotubes [40].The activity and stability of the Ni-Al 2 O 3 catalyst are reduced due to a large amount of carbon deposition on the surface of nickel, while the stability of the Ni-La 2 O 3 catalyst was well maintained due to the small amount of carbon deposition on the surface of the nickel.The oxidation of carbon deposits after methane dry reforming exhibited a similar rule (Figure 10(b)).Large amounts of carbon deposition on the surface of nickel metal cause bad stability for Ni-Al 2 O 3 which was consistent with the TEM results above (Figure 9).

Conclusions
In a word, La 2 O 3 -and Al 2 O 3 -supported Ni catalysts were prepared by the citric acid-assisted sol-gel method, and their structures, properties, and reactivity were systematically compared.Ni-La 2 O 3 with small particle size of nickel, strong metal-support interaction, rich metal-support interface, and abundant strong basic sites were achieved as verified by XRD, H 2 -TPR, TEM, and CO 2 -TPD.The catalytic performance showed that compared with Ni-Al 2 O 3 , Ni-La 2 O 3 catalyst had higher ethanol steam reforming activity, stability, and hydrogen production rate.Under the condition of 55920 mL/g cat •h of ethanol-water vapor at 600 °C, the ethanol conversion remained at 87.8% after 3000 min of reaction.The hydrogen production rate was greater than 6500 μmol/ min, and the resistance to carbon deposition was greatly improved.In addition, the Ni-La 2 O 3 catalyst showed good activity in methane dry reforming with the initial conversion rate of methane and carbon dioxide was greater than 90%, and the H 2 /CO ratio was close to 0.94.The better catalytic performance for Ni-La 2 O 3 catalyst was attributed to the smaller size of metal nanoparticles, more metal-support interfaces, rich nickel electron density, abundant strong basic sites, and strong metal-support interaction.

Figure 1 :
Figure 1: (a) XRD patterns of the reduced catalysts, ♦ and ♥ stand for Ni and La 2 O 3 , respectively.(b) H 2 -TPR profiles of the As-prepared catalysts.(c) N 2 adsorption-desorption isotherms (inset is pore size distributions) of the samples.(d) The CO 2 -TPD for the Ni-La 2 O 3 and Ni-Al 2 O 3 .

Figure 2 :
Figure 2: XPS profiles of the As-prepared catalysts.

Figure 3 :
Figure 3: TEM images of the catalysts after H 2 reduction: (a, b) Ni-La 2 O 3 and (c, d) Ni-Al 2 O 3 .The inset figure is the Ni particle size distribution.

Figure 4 :
Figure 4: (a) HAADF-STEM images; (b-d) TEM mapping of Ni, La, and O elements; and (e) overlap of elements for reduced Ni-La 2 O 3 .

Figure 5 :
Figure 5: (a) HAADF-STEM images; (b-d) TEM mapping of Ni, Al, and O elements; and (e) overlap of elements for reduced Ni-Al 2 O 3 .

Figure 6 :
Figure 6: The conversion of ethanol and gas product formation rate with time on stream at the GHSV of 55920 mL/g cat •h for C 2 H 5 OH solution, reaction conditions: T = 600 °C, H 2 O/C 2 H 5 OH = 4, P = 0:1 MPa, N 2 = 60 mL/min for (a) Ni-La 2 O 3 and (b) Ni-Al 2 O 3 for the gas product composition for the catalysts of (c) Ni-La 2 O 3 and (d) Ni-Al 2 O 3 .

Figure 2 .
For the Ni-Al 2 O 3 catalyst, Al 2p 3/2 was detected, indicating that the Al element was trivalent.Similarly, La 3d 3/2 was detected on the Ni-La 2 O 3 catalyst, indicating that the La element was also trivalent.For the Ni 2p, three peaks at 852, 856, and 861 eV could be assigned to Ni 0 , Ni 2+ , and satellite peak (Ni 2+ ), respectively.Compared with Ni-Al 2 O 3 , the binding energy of Ni 0 for Ni-La 2 O 3 shifts towards low binding energy, indicating the increased electron density of Ni 0 , which may be explained by the enhanced metal-support interaction as

Figure 8 :Figure 9 :
Figure 8: XRD analysis of the spent catalyst for (a) ethanol steam reforming and (b) methane dry reforming.

Figure 10 :
Figure 10: The TG and DTG analyses of the spent catalysts (a) after ethanol steam reforming and (b) after methane dry reforming.

Table 1 :
Textural properties of the As-prepared samples.
780 °C for 1 h under 10% vol H 2 /Ar mixture gas.The reduced catalyst was prepared, named as Ni-La 2 O 3 , and the weighted percentage of Ni was kept at 10 wt%.Similarly, the Ni-Al 2 O 3

Table 2 :
Comparison of the catalytic performances with previously reported catalysts.