Hydrogen Yield from CO 2 Reforming of Methane: Impact of La 2 O 3 Doping on Supported Ni Catalysts

: Development of a transition metal based catalyst aiming at concomitant high activity and stability attributed to distinguished catalytic characteristics is considered as the bottleneck for dry reforming of methane (DRM). This work highlights the role of modifying zirconia (ZrO 2 ) and alumina (Al 2 O 3 ) supported nickel based catalysts using lanthanum oxide (La 2 O 3 ) varying from 0 to 20 wt% during dry reforming of methane. The mesoporous catalysts with improved BET surface areas, improved dispersion, relatively lower reduction temperatures and enhanced surface basicity are identiﬁed after La 2 O 3 doping. These factors have inﬂuenced the catalytic activity and higher hydrogen yields are found for La 2 O 3 modiﬁed catalysts as compared to base catalysts (5 wt% Ni-ZrO 2 and 5 wt% Ni-Al 2 O 3 ). Post-reaction characterizations such as TGA have showed less coke formation over La 2 O 3 modiﬁed samples. Raman spectra indicates decreased graphitization for La 2 O 3 catalysts. The 5Ni-10La 2 O 3 -ZrO 2 catalyst produced 80% hydrogen yields, 25% more than that of 5Ni-ZrO 2 . 5Ni-15La 2 O 3 -Al 2 O 3 gave 84% hydrogen yields, 8% higher than that of 5Ni-Al 2 O 3 . Higher CO 2 activity improved the surface carbon oxidation rate. From the study, the extent of La 2 O 3 loading is dependent on the type of oxide support.


Introduction
The decrease of fossil fuel energy and the dilemma of environmental pollution urged a large number of researchers to maximize the conversions of methane and carbon dioxide into useful products such as hydrogen. Hydrogen is a benign source of energy. It is mainly obtained from biomass pyrolysis and thermal reforming. Methane, the main component of natural gas, can be obtained from various resources like shale gas and the fracking process, which has increased the availability of natural gas from infrequent deposits [1,2]. Moreover, the utilization of biogas is gaining momentum in recent years [3,4]. In the field of heterogeneous catalysis, particularly, in the latest decades, dry reforming of methane is regarded as one of the best prospective ways of conversion [5][6][7]. However, the dry reforming reaction as shown in Equation (1) is highly endothermic and thus requires high reaction temperatures. The process produces synthesis gas that has an appropriate ratio of H 2 to CO suitable for Fischer-Tropsch synthesis [8]. Steam reforming of methane remains the best available industrial process for generating synthesis gas [9,10]. The requirement and the utilization of synthesis gas production are continuously increasing [11]. During methane dry reforming (DRM), CO 2 is employed as an oxidant, which draws the interest and the likelihood of seizing and recycling CO 2 from the exhaust flue gases of industrial and power plants. DRM is presently not industrially applied because of the heavy coking and sintering of the catalysts in high-temperature reforming reactions [12]. Thus, it is essential to find an innovative catalyst that endures sintering and coking. The sintering of the metallic phase and carbon formation on the surface of the catalyst, which causes the deactivation, originate from operating conditions that facilitate the side reactions, which involve the cracking of the CH 4 Equation (2) and the reverse Boudouard reaction Equation (3) resulting from the combinations of CO [13].
H 2 yield through DRM is significantly affected by dissociation of CH 4 over Nisupported surface and the gasification of carbon formed by CO 2 . The reverse water gas shift reaction and the action of the H 2 spillover on the surface affect the H 2 yield substantially. The hydrogen spill over enhances hydroxyl formation and catalytic activity toward CO oxidation at the metal/oxide interface. The hydroxyl groups at the metal/support interface react with CO to produce CO 2 . Similarly, the reverse water gas shift (CO 2 + H 2 O → CO + H 2 ) reduces the hydrogen; hence, the two phenomena involve the depletion of hydrogen and in turn influence the hydrogen yield. Noble metals like Pd, Ir, Pt, and Rh provide the extremely good performance of activity and stability but they are rare and expensive [14,15]. Transition metals like Ni are suitable alternatives for this reaction as they are stable and environmentally friendly [16,17]. Nonetheless, Ni-based catalysts are hampered by poor activity due to coke formations and sintering [18,19]. Hence, the major challenge is to come up with Ni catalysts capable of resisting carbon formation and sintering. Carbon generation may be opposed by controlling the reaction kinetics using suitable catalysts with proper constituents and supports. It has been established that metal-support interactions can alter both catalyst activity and activity maintenance. Bradford and Vannice had shown that support decoration of metal particle surfaces shattered big ensembles of metal atoms that served as active sites for carbon deposition and the sites in the metal-support interfacial region enhanced catalyst activity [20]. The choice of support type plays a vital role in DRM. Supports that possess O 2 species at the surface of the catalyst help the carbon oxidation on the metal [21,22]. The balance between the rate of methane decomposition and the rate of carbon gasification regulates the catalyst stability [23]. The preparation of mesoporous oxides, like Al 2 O 3 , possessing high surface area and precise pores have revealed motivating results to disperse the metal over the support structure [24][25][26]. Bian et al., in their investigation of Ni supported home-made mesoporous alumina in methane dry reforming, indicated that the formation of NiAl 2 O 4 spinel is advantageous to activity and stability towards DRM reaction [27].
Newnham et al. synthesized nanostructured Ni-incorporated mesoporous alumina with various Ni loadings by hydrothermal method and tested them as catalysts for CO 2 reforming of methane [28]. The result displayed excellent stability when 10%Ni was used due to the fact that the Ni nanoparticles in these catalysts being highly stable towards migration/sintering under the reaction conditions. The presence of strong Ni-support interaction and/or active metal particles being confined to the mesoporous channels of the support. Al-Fatesh et al. studied dry reforming of methane using a series of nickel-based catalysts supported on γ-alumina promoted by B, Si, Ti, Zr, Mo, and W [5]. They concluded that the promoters enhanced the interaction between NiO and γ-alumina support and, hence, Ni dispersion and stability. On the other hand, ZrO 2 is prominent support with high thermal stability able to go through alteration in their acid-basic sites [29]. Numerous studies have displayed that the presence of ZrO 2 improves the thermal resistance, redox properties, oxygen storage capacity and gasification of deposited carbon [30,31]. Hu  decomposition of nickel precursor under the influence of dielectric barrier discharge (DBD) plasma at~150 • C [32]. It was found to improve activities due to the exposition of Ni (111) facets, smaller metal particles, and more tetragonal zirconia with increased oxygen vacancies. In the course of dry reforming of methane, oxygen species over the catalyst surface affected the catalytic performance and carbon deposition. Zhang et al. studied the effects of the surface adsorbed oxygen species tuned by doping with metals like La, Ce, Sm, and Y on the catalytic behavior [33]. Their results confirmed that the surface adsorbed oxygen species promoted both CO 2 activation and CH 4 dissociation. Doping La 2 O 3 in supported Ni catalysts favor the CO 2 adsorption on the surface of the catalyst [34], alters the chemical and electronic state of Ni at the interface with the support and decreases the chemical interaction between Ni and the support causing the intensification of reducibility and higher dispersion of nickel [35]. Tran et al. studied the enhancement of La 2 O 3 in the physicochemical features of cobalt supported over alumina for DRM using different temperatures and feed compositions [36]. Their results displayed that the La 2 O 3 improved the H 2 activation; enriched oxygen vacancy and lowered the apparent activation energy of CH 4 consumption. The work of Lui et al. elaborated the promotional effects of La, Al, and Mn on Fe-modified clay supported by Ni catalysts used for dry reforming of methane [37]. The result of adding La, Al, and Mn altered the surface area, the basicity of the catalysts, and produced a smaller metallic Ni size. Moreover, Yabe et al. performed dry reforming of methane using several transition metals supported on ZrO 2 catalysts [38]. Their results exhibited high activity and low carbon deposition upon using 1 wt%Ni/10 mol%La-ZrO 2 catalysts.
In the present work, we assess the effect of the lanthanum oxide as a textual promoter of alumina and zirconia supports over Ni catalysts in the catalytic reforming of CH 4 with CO 2 . The impact of different loadings of lanthanum oxide will be examined and their influence on the hydrogen yield. The output data will be further associated with the characterization results of BET, XRD, TPR, TEM, TPD, and TGA before and after the reaction. The difference in the basic supports originating from alumina and zirconia in terms of sintering and coking will be explored.

Catalyst Preparation
In the case of zirconium-based support (for 5Ni-10La-ZrO 2 ), the required amounts of zirconia (2.62 g) in the form of ZrOCl 2 ·8H 2 O was ground completely and poured into the empty crucible. Then, the desired weights of La(NO 3 ) 3 ·6H 2 O (0.265 g) and that of Ni(NO 3 ) 2 ·6H 2 O (0.25 g) were added to the crucible containing the support to get a powder mixture. The mixture was ground well in the crucible to obtain a homogenous mixture. Purified water was poured slowly to the mixture to produce a paste while mixing. The paste was set to evaporate under room temperature condition until it dried. Thereafter, the dried sample was calcined at 700 • C for 3 h. The obtained catalysts were denoted as 5Ni-ZrO 2 for 5 wt% Ni supported over ZrO 2 , and 5Ni-xLa-ZrO 2 , where x = 10, 15, 20 wt%.
In the case of alumina-based support, the above-mentioned procedure was adopted by replacing zirconia with the required amounts of mesoporous γ-Al 2 O 3 . The obtained catalysts were denoted as 5Ni-Al 2 O 3 for 5 wt% Ni supported over Al 2 O 3 and 5Ni-xLa-Al 2 O 3 , where x = 10, 15, 20 wt%.

Catalyst Characterization and Activity
The catalyst activity test and characterization are described in detail in the supplementary information.

Results and Discussion
The surface texture of the catalysts was assessed via the nitrogen adsorption-desorption isotherms. Figure 1A shows the nitrogen adsorption isotherms of the fresh catalysts (5Ni-xLa 2 O 3 -ZrO 2 , x = 0, 10, 15, and 20 wt%) and according to IUPAC labelling, catalysts are showing type IV isotherm with capillary condensation appearing at a relative pressure below the saturation pressure, and H1 hysteresis loop. These features are associated with mesoporous materials that have cylindrical pore geometry with narrow size distribution as well as relatively high uniformity [39]. Figure 1B exhibits the nitrogen adsorption isotherms of the fresh catalysts (5Ni-x%La-Al 2 O 3 ). All samples indicate typical type IV adsorption/desorption isotherms with H1 hysteresis loop. Point of inflection at a relative pressure in the range of 0.6-0.75 corresponds to the capillary condensation which indicates the uniformity of the pores in mesoporous material [40,41].The textural properties of the catalyst are given in Table S1 of the supplementary.  (Figure 2A), two prominent reduction maxima are detected over the entire temperature range, which may be attributed to the reduction of different NiO species (NiO→Ni 0 ). The first reduction peak situated in region I at Tmax = 298 • C could be ascribed to the reduction of free NiO that is not attached to the support, and hence reduces easily at low temperature. Further, the peak in the region II at Tmax = 468 • C is allotted to the NiO reduction, attached to ZrO 2 by a moderately strong link and its reduction requires higher thermal energy. After support modification by means of La 2 O 3 , substantial variations in reduction kinetics were detected. Reduction maxima illustrating NiO reduction for the higher temperature peaks has shifted towards lower temperatures [42]. In the case of Figure 2B, the 5% Ni-x% La 2 O 3 -Al 2 O 3 catalysts (x = 0, 10, 15, and 20) display a single peak in region III at higher temperatures. The un-promoted 5%Ni-Al 2 O 3 catalyst shows a broad peak at 750 • C indicating that the reduced NiO is strongly attached to the support. When the support is modified with the addition of different loadings of La 2 O 3 , peaks of relatively lower areas appear at high temperatures. The La 2 O 3 modified support catalyst is shifted to higher temperatures [43]. The highest La 2 O 3 loading catalyst gives the highest peak shift. This means that the addition of La 2 O 3 increases further the interaction between the NiO and the modified support. The    Figure 3A has two crystalline phases, tetragonal zirconia (t-ZrO 2 ) and monoclinic zirconia (m-ZrO 2 ). The peaks at 25.5 • and 34.3 • are ascribed to m-ZrO 2 [44,45], while the peaks at 40.9 • , 50.2 • , and 55.5 • are credited to t-ZrO 2 [46]. In Figure 3B   5Ni-10La 2 O 3 -ZrO 2 . The highest hydrogen yield of about 80% is recorded using 10% La 2 O 3 . The improvement due to the La 2 O 3 addition is attributed to the fact that La 2 O 3 increases the dispersion of Ni particles on the supports and reduces the agglomeration of Ni particles during the reforming reaction as depicted in Figure 2A. Moreover, La 2 O 3 increases the basicity as shown in the TPD profiles and therefore adsorb and react with CO 2 to form La 2 O 2 CO 3 species on the surface of catalyst which can speed up the conversion [49]. ZrO2 is discussed in this section. The initial hydrogen yield of the 5Ni-ZrO2 catalyst in Figure 4 is lower than the La2O3 modified catalysts. An evident trend is noted when La2O3 is added causing a significant improvement in the DRM performance. The improvement profile escalates as the following: 5Ni-ZrO2 < 5Ni-20La2O3-ZrO2 < 5Ni-15La2O3-ZrO2 < 5Ni-10La2O3-ZrO2. The highest hydrogen yield of about 80% is recorded using 10% La2O3. The improvement due to the La2O3 addition is attributed to the fact that La2O3 increases the dispersion of Ni particles on the supports and reduces the agglomeration of Ni particles during the reforming reaction as depicted in Figure 2A. Moreover, La2O3 increases the basicity as shown in the TPD profiles and therefore adsorb and react with CO2 to form La2O2CO3 species on the surface of catalyst which can speed up the conversion [49]. In Figure 5, the hydrogen yield obtained is close for La2O3 doped and non-doped catalysts. The La2O3 addition improved marginally the hydrogen yield in the following manner 5Ni-Al2O3 < 5Ni-20La2O3-Al2O3 < 5Ni-10La2O3-Al2O3 < 5Ni-15La2O3-Al2O3. The 15% La2O3 gave the highest hydrogen yield of 84%. It can be inferred that the effect of La2O3 loading affects differently the hydrogen yield productivity depending on the type of the support. Table 1 describes the efficiency of the present work and some of the literature.  In Figure 5, the hydrogen yield obtained is close for La 2 O 3 doped and non-doped catalysts. The La 2 O 3 addition improved marginally the hydrogen yield in the following manner 5Ni-Al 2 O 3 < 5Ni-20La 2 O 3 -Al 2 O 3 < 5Ni-10La 2 O 3 -Al 2 O 3 < 5Ni-15La 2 O 3 -Al 2 O 3 . The 15% La 2 O 3 gave the highest hydrogen yield of 84%. It can be inferred that the effect of La 2 O 3 loading affects differently the hydrogen yield productivity depending on the type of the support. Table 1 describes the efficiency of the present work and some of the literature.   Figure 6 exhibits the CO 2 -TPD profiles of the (A) 5Ni-xLa 2 O 3 -ZrO 2 and (B) 5Ni-xLa 2 O 3 -Al 2 O 3 (x = 0, 10, 15, and 20 wt%) spent catalysts obtained at 700 • C reaction temperature. This was performed to scan the surface basicity of the catalysts, which plays a vital role in the catalytic DRM reaction [54]. It is commonly understood that a greater desorption temperature of CO 2 reveals a stronger basicity and a bigger amount of CO 2 desorption although signifying that more basic sites are presented on the surface of catalyst [55]. In Figure 6A, three chief CO 2 desorption peaks were identified in the experimented temperature range from 50 to 700 • C for higher loadings of La 2 O 3 (5Ni-15La 2 O 3 -ZrO 2 and 5Ni-20La 2 O 3 -ZrO 2 ) modified catalysts and only two peaks for the un-modified (5Ni-ZrO 2 ) and lower loading La 2 O 3 (5Ni-10La 2 O 3 -ZrO 2 ) modified catalysts, which denoted that three types of basic sites existed in the 5Ni-xLa 2 O 3 + ZrO 2 (x = 0, 10, 15, and 20 wt%) catalysts. The CO 2 desorption peaks appeared at 80 • C, 260 • C and 550 • C. The peaks correspond to the weak adsorption of CO 2 on OH groups, moderate adsorption of CO 2 and strong CO 2 adsorption on the metal-oxygen pairs and O 2− anions, respectively [56,57]. It is clear that CO 2 was favorably absorbed on the strong basic sites as the support was modified with La 2 O 3 , rather than bare zirconia support. This result showed that the adsorption of CO 2 had altered from physical adsorption to chemical adsorption because of the addition of La 2 O 3 . Figure 6B shows two main CO 2 desorption peaks at 80 • C and 250 • C corresponding to weak and moderate basic sites. Hence, the addition of La 2 O 3 to the support did give significant variation in basicity of the 5Ni-xLa 2 O 3 + Al 2 O 3 catalysts. The 5Ni-15La 2 O 3 -Al 2 O 3 displays larger peak intensity than the remaining catalysts, which is in accordance with the better activity observed. Table 2 shows a summary of a quantitative assessment of CO 2 adsorption of the spent catalysts via CO 2 -TPD for ZrO 2 and Al 2 O 3 supported catalysts.   Figure 7A,B contain images obtained from Energy-dispersive X-ray spectroscopy (EDX) analysis of the fresh samples of both 5Ni-10La 2 O 3 -ZrO 2 and 5Ni-15La 2 O 3 -Al 2 O 3 . These results show the elemental composition of the as-prepared catalyst samples. First, the analysis confirmed the presence of all the elemental constituents that were mixed together during the catalyst synthesis. Moreover, the percentage loadings revealed by the EDX analysis are virtually the same as intended in the calculation and catalyst preparation with error values of 10% for Ni and 6% for La. Broad examination of the morphology of catalysts was performed via TEM. Typical TEM overviews of the fresh catalysts ( Figure 8A,C) and spent catalyst samples ( Figure 8B,D) were acquired after DRM at 700 • C for 420 min time on stream. There is a difference in the morphology of the fresh and used catalysts. The fresh catalyst seems to have particles clumped on the surface, while the spent catalysts depict rough and dispersed particles on the catalyst surface. In addition to the recognized metal particles, carbon in the form of nanotubes can be seen in the images of the used catalysts. The image of the fresh 5Ni-10La 2 O 3 -ZrO 2 catalyst is shown in Figure 8A. It is evident from the TEM images that the Ni is homogeneously dispersed over the surface of the support. In contrast to its spent sample as shown in Figure 8B, big quantities of coke are formed commonly in the form of nanotubes. The TEM images showed well dispersed Ni species ((average particle diameter of 4 nm) over La 2 O 3 -Al 2 O 3 support ( Figure 8C). However, after the reaction ( Figure 8D) size of Ni species has grown (average particle diameter of 7-8 nm). The Fourier Transform Infrared Spectroscopy (FTIR) analysis of fresh 5Ni-ZrO 2 , 5Ni-10La 2 O 3 -ZrO 2 , 5Ni-Al 2 O 3 and 5Ni-15La 2 O 3 -Al 2 O 3 catalysts were done to investigate the existing bonds within the catalyst system. The infrared spectra of absorption for these samples are shown in Figure 9A,B. In Figure 9A, Al 2 O 3 is well known for its tendency to adsorb moisture from the atmosphere onto itself. Thus, the distinct band representing the stretching vibration of O-H, within the wavelengths 3430-3460 cm −1 for all the samples can be ascribed to [OH] −1 groups interaction and/or physisorbed moisture interaction that is adsorbed onto the Al 2 O 3 support [58]. It is noticeable from the figure that the extent of hydration of the catalyst surface changed with metal addition as the OH band's intensity decreased on adding active metal. Moreover, the vibration bands centered at around 1400, 1520, 1649, and 2366 cm −1 can be seen for the support and the other samples. This implies that these bands can be associated with the support, the Al-O bond stretching to be specific [59]. The small less noticeable peaks appearing at wavelengths 1237 and 1719 cm −1 for the 5Ni-Al 2 O 3 sample can be said to be the stretching vibration of NiO and NiAl 2 O 4 species, respectively. The latter is thought to have stronger interaction with the support, in light of that it appeared at a higher wavelength.
As for the ZrO 2 support and ZrO 2 supported catalysts ( Figure 9B); the band within 3357-3440 cm −1 can be said to be hydrogen-bonded bending and stretching of the OH groups as a result of adsorbed moisture while the peaks at 1632-1640 cm −1 can be assigned to the vibration of the water molecules [60]. These peaks are seen to decrease in intensity with the addition of nickel and lanthanum oxide to the support. The peaks that are centered at around 457 and 752 cm −1 represent the asymmetric stretching of the Zr-O-Zr bond [61]. The vibration owing to the presence of La 2 O 3 was not discovered. This further supports the results obtained from the XRD analysis of samples with La 2 O 3 . Figure 10A displays TGA profiles of spent 5Ni-xLa 2 O 3 + ZrO 2 (x = 0, 10, 15, and 20 wt%) catalysts operated at 700 • C. The weight loss above 500 • C was due to the removal of deposited carbon. The extents of carbon deposition on the spent catalysts exhibit the following sequence: 5Ni-10La 2 O 3 -ZrO 2 < 5Ni-15La 2 O 3 -ZrO 2 < 5Ni-20La 2 O 3 -ZrO 2 < 5Ni-ZrO 2 . The un-promoted ZrO 2 catalyst gives the highest weight loss of 47.4%. The results are well established with the catalytic performance. Similarly, Figure 9B shows the TGA profiles of spent 5Ni-xLa 2 O 3 + Al 2 O 3 (x = 0, 10, 15, and 20 wt%) catalysts at 700 • C. The amounts of weight loss are close to each between the La 2 O 3 promoted and non-promoted catalysts. Since values range between 9.0% for 5Ni-10La 2 O 3 -Al 2 O 3 and 17.2% for 5Ni-ZrO 2 , this indicates the Al 2 O 3 supported catalysts are more resistant to carbon deposition than ZrO 2 supported catalysts.  Figure 11 shows the Raman analysis of the used catalysts (5Ni-ZrO 2 , 5Ni-10La 2 O 3 -ZrO 2 , 5Ni-Al 2 O 3 , and 5Ni-15La 2 O 3 -Al 2 O 3 ). The D (deformation) and G (graphitic) bands appear at nearly 1342 and 1580 cm −1 respectively except for spent 5Ni-Al 2 O 3 with D and G bands appearing at about 1468 and 1532 cm −1 , respectively. The spent catalysts are characterized by carbon deposits of different degree of graphitization. It is established that carbon deposits having high I G to I D ratio show better extent of graphitization [62]. From the figure, it can be seen that 5Ni-ZrO 2 had the highest degree of graphitization followed by 5Ni-Al 2 O 3 . Moreover, it can be inferred that the graphitization decreases with the addition of La 2 O 3 . Thus, La 2 O 3 promotes the formation carbons that are defective. Figure 11. Raman spectra for the spent catalysts (5Ni-ZrO2, 5Ni-10La2O3-ZrO2, 5Ni-Al2O3, and 5Ni-15La2O3-Al2O3) showing the extent of graphitization of the carbon deposits.

Conclusions
This paper elucidates the role of La2O3 addition to two different supports (ZrO2 and Al2O3) of Ni-based catalysts for the hydrogen production via CO2 reforming of methane. The 5Ni-10La2O3-ZrO2 catalyst increased the hydrogen yield by 25% in comparison with the pristine 5Ni-ZrO2. Similarly, the 5Ni-15La2O3-Al2O3 catalyst showed improved efficiency of 8% of hydrogen yield. The La2O3 loading influenced differently the ZrO2 and the Al2O3 supports. The study displayed that the modified La2O3-Al2O3 support catalysts gave a higher hydrogen yield than La2O3-ZrO2 supported catalyst. The catalyst characterizations showed that La2O3 addition improved specific surface areas, dispersion, reducibility, metal-support interaction, and surface basic sites which contributed towards the enhanced hydrogen yield. The qualitative and quantitative analysis of carbon formed over the spent catalysts using TEM, TGA, and Raman spectroscopy showed presence of carbon nanotubes. This work provides an insight towards the role of support modification during DRM.
Supplementary Materials: The following are available online at www.mdpi.com/xxx/s1, Table S1: Textural properties of different catalysts supported Ni catalysts: BET specific surface area (SBET), pore volume (PV), and pore diameter (DP), Table S2: The quantitative analysis of H2 consumption during H2-TPR.
Author Contributions: A.A.-F., A.I. and S.K. synthesized the catalysts, carried out all the experiments and characterization tests, and wrote the manuscript. W.K. and M.S. prepared the catalyst and contributed to proofreading of the manuscript. A.A. and A.F. contributed to the analysis of the data and writing-review of the manuscript. All authors have read and agreed to the published version of the manuscript.

Conclusions
This paper elucidates the role of La 2 O 3 addition to two different supports (ZrO 2 and Al 2 O 3 ) of Ni-based catalysts for the hydrogen production via CO 2 reforming of methane. The 5Ni-10La 2 O 3 -ZrO 2 catalyst increased the hydrogen yield by 25% in comparison with the pristine 5Ni-ZrO 2 . Similarly, the 5Ni-15La 2 O 3 -Al 2 O 3 catalyst showed improved efficiency of 8% of hydrogen yield. The La 2 O 3 loading influenced differently the ZrO 2 and the Al 2 O 3 supports. The study displayed that the modified La 2 O 3 -Al 2 O 3 support catalysts gave a higher hydrogen yield than La 2 O 3 -ZrO 2 supported catalyst. The catalyst characterizations showed that La 2 O 3 addition improved specific surface areas, dispersion, reducibility, metal-support interaction, and surface basic sites which contributed towards the enhanced hydrogen yield. The qualitative and quantitative analysis of carbon formed over the spent catalysts using TEM, TGA, and Raman spectroscopy showed presence of carbon nanotubes. This work provides an insight towards the role of support modification during DRM.