Sequential Impregnation Research Articles

Synthesis and Characterization of NiWS2/MWCNT Nanohybrids

AbstractThe present research work mainly focuses on the synthesis and characterization of NiWS2/MWCNT‐f nanohybrids. Multi‐walled carbon nanotubes MWCNT‐r were previously purified with HCl to obtain MWCNT‐p, then were treated with an acid mixture of HNO3 : H2SO4 (6 M) at 1 : 3 v/v to generate functionalization on the surface with oxygen as hydroxylic and carbonyl groups to obtain MWCNT‐f. The synthesis of the nanohybrids was carried out by the sequential incipient impregnation method using ammonium thiotungstate (ATT) and nickel chloride as metal precursors. The effect of nickel was evaluated by modifying its atomic ratio with respect to tungsten with values of R= (Ni/Ni+W) equal to 0.3 and 0.5. Subsequently, the nanohybrids were obtained by thermal decomposition in argon atmosphere and an activation method using H2/H2S. Once the nanohybrids were obtained, their structural properties were characterized by Raman spectroscopy, BET, HRTEM, XRD, and TGA analyses. The formation of the nanohybrids was achieved obtaining the active phase WS2 and NiWS supported on MWCNT‐f, which was corroborated by HRTEM and XPS spectroscopy techniques. These materials are important candidates as catalysts in the hydrodesulfurization reactions.

Promoting effect of Fe on Pt/ZSM-5 catalysts for propane dehydrogenation

Propane dehydrogenation (PDH) is an attractive method for propylene production. PtxFe/ZSM-5 catalysts were prepared by the sequential incipient wetness impregnation of Fe and Pt on ZSM-5 support. The promoting effect of Fe on the catalytic performance of PtxFe/ZSM-5 during propane dehydrogenation reaction was studied. Various characterization techniques including N2 adsorption/desorption, ICP-OES, HRTEM, XPS, CO-DRIFT and TG were employed to unravel the properties of the catalysts. The experimental results confirmed the importance of Fe as a promotor in PDH. Suitable loading of Fe could obviously improve propane conversion, propylene selectivity, and the anti-coking ability of the catalysts, while excessive Fe caused metal aggregation and promoted side reactions, leading to a decreased propylene selectivity. When Fe loading was 1.0%, the resulting Pt1.0Fe/ZSM-5 exhibited the best catalytic performance (propane conversion = 47.1%, and propylene selectivity = 78.9%), and it also showed good catalytic stability after regeneration. Pt0.5Fe/ZSM-5 showed the lowest coke amount of 0.10 gc·gcat−1, and the addition of 0.5% Fe in Pt/ZSM-5 catalyst decreased 61.5% of coke deposits.

AuPd/TiO2 Catalysts in the CO Oxidation: Insights into the Synthesis Procedure and In-situ Spectroscopy Studies

Abstract A series of bimetallic AuPd/TiO2 catalysts (Au/Pd = 1) were prepared through either the impregnation or the deposition-precipitation in urea (DPU) approach and tested in the CO oxidation reaction. Among these, the sample synthesized through a sequential impregnation (Pd) followed by DPU (Au), with an intermediate thermal treatment in air, presented a remarkable CO conversion at sub-ambient temperatures and an enhanced catalytic stability, compared to the monometallic samples. The ex-situ characterization revealed that the synthesis procedure led to the formation of well-dispersed bimetallic AuPd nanoparticles over the TiO2 support. The in-situ characterization helped to propose that bimetallic NPs were composed of an intermetallic Au-Pd phase with both atoms available in the surface. Both in-situ FTIR and UV-vis spectroscopies helped to recognize the active sites during the reaction: Au in close interaction with the TiO2 at low temperatures, and step/edges Pd sites at high temperatures. Finally, the pivotal role of the TiO2 reducibility in the CO oxidation reaction, promoted by the bimetallic AuPd NPs, was determined through in-situ Raman spectroscopy.

Insight into the influence of Re and Cl on Ag catalysts in ethylene epoxidation.

Commercial ethylene epoxidation catalysts consist of α-alumina supported Ag particles and usually contain a mixture of promoters. High selectivity catalysts typically include a small amount of rhenium species. We studied a series of Ag catalysts promoted with Re loadings up to 4 at% (Re/(Re + Ag)), which is intentionally higher than in optimized commercial catalysts to facilitate characterization and to amplify the influence on catalysis. Sequential impregnation brought Re and Ag in such close contact that they formed a new characterized phase of AgReO4. Chemisorption experiments showed that both ReO x and AgReO4 species act as a reversible reservoir for O2. Ethylene epoxidation was performed without and with the industrially crucial ethyl chloride promoter in the feed. Without the chloride (Cl), the ethylene oxide selectivity increased when Re was present, whereas the combination of Re and Cl decreased the ethylene oxide selectivity at higher Re loadings. Systematic ethylene oxide isomerization experiments revealed that Re and Cl individually inhibit the isomerization on the Ag surface. However, Re and Cl combined increased the isomerization, which can be explained by the surface becoming overly electrophilic. This hence shows the importance of studying promoters both individually and combined.

Improvement of carbon paper performance by adding carbon nanofibers to carbon paper and impregnation

Carbon paper, as a key component in proton exchange membrane fuel cells (PEMFCs), had attracted much attention due to its corrosion resistance, electrical conductivity and mechanical strength as well as gas permeability. The incorporation of carbon nanofibers (CNFs) into carbon paper can further enhance its electrical conductivity and other properties. Herein, prepared carbon paper precursors (CPP) via wet papermaking and optimized the process through resin impregnation and hot pressing. The addition of CNFs, particularly at 10 %, significantly improved electrical conductivity and mechanical properties, reducing resistivity by 23.9 % and maximizing tensile strength of 36.97 N·m/g. The sequence of CNFs application and resin impregnation, specifically the spray-after-impregnation (S-I) method, was crucial for achieving these enhancements. Our findings offer a strategy for fabricating high-performance carbon paper, crucial for PEMFC efficiency and durability.

Highly Efficient Ru-VOx/TiO2 Catalysts for Hydrodeoxygenation of Amides to Amines: The Promotion Effect of Monolayer Dispersed VOx on Rutile TiO2.

The hydrodeoxygenation of amide to amine is one of the most important amine synthetic approaches in chemical engineering. However, low amide reactivity and poor amine selectivity remain big challenges for catalytic hydrodeoxygenation of amides. Here, Ru-VOx/TiO2 catalysts with different V/Ru atomic ratios were prepared with the sequential impregnation method. The physicochemical properties of catalysts were characterized by using XRD, Raman, TEM, CO chemisorption, NH3-TPD, H2-TPR, XPS, and Formamide-DRIFTS. The hydrogenation of butyramide as a model reaction was used to evaluate the catalytic performance. The butyramide conversion and butylamine selectivity varied with V/Ru atomic ratio in a volcano-type relationship, and the 2V-4Ru/TiO2 catalyst (V/Ru atomic ratio = 1) presented the best catalytic performance (96% conversion and 82% butylamine selectivity) at 423 K with 5 MPa H2. The catalyst was also reused five successive times without an obvious decline in either activity or selectivity, showing excellent stability. Based on characterization and evaluation results, the interaction between Ru nanoparticles (∼2 nm) and VOx species promoter generated abundant Ru-VOx boundary with V4+ species adjacent to oxygen vacancies (Ru-Vo-V4+). As the V/Ru atomic ratio was 1, the 2V-4Ru/TiO2 catalyst, with monolayer dispersed VOx species, presented the maximum Ru-VOx boundary and showed the best catalytic activity and selectivity to amine. The monolayer dispersed VOx species also minimized the catalyst surface acidity and suppressed the secondary side reaction. Moreover, the hydrodeoxygenation reaction evaluations of various amides including aliphatic primary amides and cyclic amides showed 90-99% conversion and 78-99% selectivity to corresponding amines, suggesting wide applicability of 2V-4Ru/TiO2 catalyst. The study provides a highly efficient strategy to improve amine selectivity in the hydrodeoxygenation of amides by optimizing the interaction between metal and metal oxide promoters.

Nanostructured Ni–Co catalysts: Effect of impregnation sequence and complexing agent

This paper explores the synthesis by the impregnation method using citric acid and the characterization of bimetallic Nickel–Cobalt (Ni–Co) catalysts, focusing on their application in ethanol steam reforming leveraging the demonstrated improved stability and catalytic activity observed in previous works when Co is introduced into Ni catalysts. The study aims to investigate the effects of the sequence of incorporation of Ni and Co in the catalyst support in order to optimize the catalytic performance. The results indicate that the optimal sequence for introducing Co and Ni significantly enhanced the catalytic performance in ethanol steam reforming and it was associated to a higher Ce+3/Ce+4 ratio and a stronger active site-support interactions that modified the CNT growth mechanism, preventing increasing pressure drop through the reactors. The best catalytic performance corresponded to the system, Co/Ni/MgAl2O4–CeO2, in which Co was incorporated after Ni.

Al2O3 Concentration Effect on Deep Hydrodesulfurization of 4,6-Dimethyldibenzothiophene over NiWS/Al2O3-ZrO2 Catalysts.

The Al2O3 concentration effect over NiWS/Al x Zr100-x catalysts was investigated for deep hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene (4,6-DMDBT). The sol-gel method changed the wt % Al2O3 concentrations used to synthesize the Al x Zr100-x supports. The NiWS/Al x Zr100-x catalysts were prepared with ammonium metatungstate hydrate and nickel(II) nitrate hexahydrate by sequential incipient impregnation, calcination, and H2S/H2 activation. The catalytic evaluation data fit a pseudo-first-order trend in the 4,6-DMDBT HDS reactions. In the oxide phase, the catalysts presented Ni and W species in tetrahedral (td) and octahedral (oh) coordination, with the oh species prevailing as a function of the Al2O3 amount. The lower amount of Al2O3 can facilitate the "Type II" NiWS phase formation by weakening the interaction of the W-O-Al bond and promoting W and Ni species sulfidation. In the sulfide phase, catalysts with (oh) coordination and surface WO X species promote the formation of WS2 and NiWS species during the catalyst activation step. This species favors the reaction yield, where the hydrogenation route is predominant, with the highest initial reaction rate using the NiWS/Al25Zr75 catalyst. A direct correlation was found between high hydrogenation/hydrogenolysis ratio values and low Al2O3 concentrations.

Support Screening to Shape Propane Dehydrogenation SnPt-Based Catalysts.

Propane dehydrogenation reaction (PDH) is an extremely attractive way to produce propylene; however, the catalysts often lead to byproduct formation and suffer from deactivation. This research focuses on the development of efficient Pt/Sn-based shaped catalysts by utilizing Mg-modified mesoporous silica, sepiolite (natural SiMgO x mesoporous clay), and sepiolite/bentonite/alumina as supports with the aim of achieving superior stability and selectivity for industrial propylene production by PDH. The catalysts were prepared by sequential impregnation of the supports with the corresponding solutions of tin chloride and platinum chloride, by obtaining a nominal loading of 0.7 wt % of Sn and 0.5 wt % of Pt. A range of analytical techniques were used to characterize the catalysts, including X-ray diffraction, nitrogen physisorption isotherms, Hg intrusion porosimetry, thermogravimetric analyses, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The basicity of the catalysts was assessed using carbon dioxide temperature-programmed desorption (CO2-TPD). The results confirm that the support material plays a critical role in catalyst performance; in particular, the presence of weak basic sites, due to magnesium addition, improved selectivity to propylene and reduced coke formation. Catalytic pellets of Sn-Pt supported on macroporous sepiolite or sepiolite and bentonite-modified mesoporous alumina performed comparably with propane conversion very close to thermodynamic equilibrium and selectivity to propylene above 95%. The latter support led to improved stability and was regenerated at milder temperatures, making it suitable for industrial applications.

Optimization of greenhouse gas valorization over ceria‐promoted Co–Ni/graphene oxide catalytic materials using response surface methodology

AbstractBackgroundThe mitigation of global warming effect requires intensified research efforts to reduce greenhouse gas emissions. This study was aimed at investigating the valorization of two principal greenhouse gases, namely carbon dioxide (CO2) and methane (CH4), over CeO2‐doped Co–Ni/GO catalytic materials. The CeO2‐doped Co–Ni/GO catalysts were synthesized using a sequential wet impregnation method and employed for CO2 reforming of CH4. The catalytic materials were characterized using various instrumental techniques. Response surface methodology (RSM) was employed to investigate the impact of process factors, namely reaction temperature (ranging from 700 to 800 °C), CeO2 loading (ranging from 5% to 15%) and feed flowrate (ranging from 10n to 50 mL min−1), on the CH4 conversions.ResultsThe three factors were observed to have significant influence on the CH4 conversion based on analysis of variance. The analysis of the RSM quadratic model revealed that the optimum conditions of 800 °C, 14.22% and 10.00 mL min−1 were obtained for the reaction temperature, CeO2 loading and feed flowrate resulting in maximum CH4 conversion of 98.24%. The desirability function for these results was calculated to be 0.934. The predicted process parameters aligned with the results of the actual experimental analysis.ConclusionThis study has demonstrated that the conversion of CH4 to value‐added products such as syngas can be optimized using RSM. The optimum conditions obtained could be used to improve the process performance. © 2024 Society of Chemical Industry (SCI).

Facile fabrication method of nanocomposite pore filling ion exchange membrane: Impregnation method using dispersion solution of inorganic particles

Research on composite ion exchange membranes (IEMs) focuses on compensating the limitations of homogenous IEMs. The fabrication of nanocomposite IEMs is relatively complex, as the dispersion of inorganic substances within a polymer matrix must be considered. In this study, we propose a simple method for preparing nanocomposite IEMs by combining a porous substrate and dispersion solution with inorganic nanoparticles. The nanocomposite porous substrate with nanoparticles is prepared by impregnating a solution into a porous substrate, where the nanoparticles penetrate the nanosized pores of the substrates by capillary forces. Subsequently, nanocomposite pore-filling IEMs (PIEMs) are fabricated by impregnating an electrolyte solution into the substrate and photopolymerization. Impregnation applies to the manufacture of nanocomposite PIEMs, regardless of the type, surface conditions, and size of inorganic particles in dispersion. Through the sequential impregnation of dispersion solutions, single- and multi-component PIEMs containing more than one type of nanoparticle are manufactured. The increased interconnectivity of ion conduction channels in PIEMs by nanoparticles causes permselectivity improvement in nanocomposite PIEMs. However, compared to PIEMs without inorganic particles, the addition of inorganic particles results in a lower electrolyte polymer content in the PIEMs, leading to deterioration of the ion exchange capacity and resistance of nanocomposite PIEMs.

Effect of the amount and type of active metal and its impregnation sequence on bio-fuel production

This study aims to investigate biofuel production from biomass-derived bio-oil and examine the impact of selecting different active metals, their quantities, and synthesis procedures on biofuel selectivity. For this purpose, alumina-supported catalysts containing Zr, Co, and W were prepared using the wet impregnation method. Some physical and chemical properties of the synthesized catalysts were determined through XRD, BET, SEM/EDS, ICP-MS, TGA-DTA, and DRIFTS analysis. The activity test studies revealed that the 5Co-10Zr@MA catalyst, prepared by co-impregnation, exhibited the highest bio-oil conversion (95 %) and the highest iso-paraffin selectivity (93 %). XRD analysis indicated that this catalyst possess the CoAl2O4 structure, indicating the formation of an alloy between alumina and cobalt, thereby enhancing catalytic activity. The reusability tests showed that the 5Co-10Zr@MA catalyst maintained its activity over a time of 3 h. Consequently, the utilization of mesoporous alumina-supported bimetallic catalysts has proven to be successful in the production of biofuels, achieving high conversion and selectivity.

Response surface optimization of hydrogen-rich syngas production by methane dry reforming over bimetallic Mn-Ni/La2O3 catalyst in a fixed bed reactor

The present work utilizes a response surface optimization technique to optimize hydrogen-rich syngas production through the process of methane dry reforming (DRM). This optimization is achieved by employing a bimetallic Mn–Ni/La2O3 catalyst. The study aimed to evaluate the impact of three key parameters, namely reaction temperature, time on stream (TOS), and gas hourly space velocity (GHSV), on the hydrogen to carbon monoxide (H2/CO) ratio in syngas during the DRM. The Mn–Ni/La2O3 catalyst, synthesized using the sequential wet impregnation technique, exhibited suitable physicochemical properties necessary for DRM reaction, as evidenced by the obtained characterization data. Among the five models examined, it was found that the quadratic versus 2FI model substantially fit the experimental data, as evidenced by a p-value <0.05. The analysis of variance (ANOVA) conducted on the quadratic response surface model compared to the 2FI model demonstrated that both the reaction temperature and the TOS had a significant impact on the H2/CO ratio in the syngas. The only significant interaction factor was the relationship between the reaction temperature and the TOS. Under the specified optimal circumstances of 15 000 ml/g.h, 850 °C, and 258.15 min, an H2/CO ratio of 0.98 was achieved. The resulting H2/CO ratio of 0.98 is almost 1, indicating its suitability as a feedstock for methanol production in the Fischer-Tropsch synthesis (FTS).

The application of Ni and Zr modified ZSM-5 nanosheet in upgrading of lignite pyrolysis volatiles coupling with methanol to light aromatics

Ni and Zr modified nanosheet ZSM-5 zeolites as tandem catalysts were designed using co-impregnation method (Zr-Ni/S-Z5) or combining in-situ hydrothermal synthesis of Ni@S-Z5 and sequential impregnation of Zr (Zr/Ni@ S-Z5). Their applications in upgrading of lignite pyrolysis volatiles coupling with methanol to light aromatics were investigated. The results demonstrated that nanosheet zeolites with larger surface areas and shorter b-axis length benefited the production of light aromatics due to exposing more active sites and improved diffusion limitation compared with conventional ZSM-5 zeolites. Adding Ni and Zr into tandem catalysts further enhanced BTEXN yields, which was attributed to the induction of oxyphilic ZrO2 for activating CAr-O bonds combining the promotion of Ni for hydrogenation. Comparing to Zr-Ni/S-Z5 catalyst, lower BTEXN yield was observed due to the decrease in exposing active sites over Zr/Ni@ S-Z5 catalyst. Moreover, enhancing diffusion behaviors in shorter b-axis length and the presence of more fractions of external coke indicated less effective in blocking pore channels, thus nanosheet zeolite series showed lower deactivation rates.

A novel Pd-doped perovskite-based LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst enhances NOx to ammonia reaction

The effect of Pd doping on the NOx removal efficiency and NH3 selectivity was studied over lean NOx trap LaCo1-xPdxO3-Ba/Al2O3-type catalysts. Two catalysts were prepared by the sequential impregnation of 15 wt% of LaCo1-xPdxO3-type perovskites and 20 wt% of barium over alumina. The results of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, temperature programmed techniques, UV–vis diffuse reflection absorption spectroscopy, and X-ray photoelectron spectroscopy demonstrated that perovskite and barium grains uniformly distribution over the alumina surface. Cobalt partial substitution by palladium changed the chemical coordination environment, thus leading to the redox properties of perovskites getting different. Moreover, the LaCoO3–Ba/Al2O3 catalyst exhibited a high reduction on NOx by H2 between 450 and 550 °C. Whereas Pd-doped LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst decreased the best activity interval around 100 °C, as well as improved the NH3 selectivity. The NOx reduction conversion of the LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst increased significantly from 72.9% to around 100% at H2/NO ratio = 1, and the production of NH3 was increased from 20.1% to 58.6% at H2/NO ratio = 3.

Preparation of highly adsorptive biochar by sequential iron impregnation under refluxing and pyrolysis at low temperature for removal of tetracycline

Iron-doping modification is a prevailing approach for improving adsorption capability of biochar with environmental friendliness, but usually requires high temperature and suffers from iron aggregation. Herein, a highly adsorptive biochar was manufactured via sequential disperse impregnation of iron by refluxing and pyrolysis at low temperature for eliminating tetracycline (TC) from aqueous solution. Iron oxides and hydroxides were impregnated and stably dispersed on the carbon matrix as pyrolyzed at 200 °C, meanwhile abundant oxygen and nitrogen functional groups were generated on surface. The iron-doped biochar exhibited up to 891.37 mg/g adsorption capacity at pH 5, and could be recycled with high adsorption capability. The adsorption of TC should be mostly contributed to the hydrogen bonding of N/O functional groups and the hydrogen bonding/coordination of iron oxides/hydroxides. This would provide a valuable guide for dispersedly doping iron and conserving functional groups on biochar, and a super iron-doped biochar was prepared with superior recyclability.

Hydrogenolysis of glycerol without external H2 over Nb-doped Ni catalysts supported on ordered mesoporous alumina

The correlation between the physico-chemical properties of Nb-doped nickel supported on ordered mesoporous alumina catalysts and product distribution during hydrogenolysis of glycerol with in situ produced hydrogen in continuous was investigated. The synthesis of alumina was carried out by the evaporation induced self-assembly (EISA) method. To achieve different interaction strengths among Ni, Nb and Al, the catalysts were prepared by co-impregnation of Ni and Nb on alumina, successive impregnation on alumina, and Ni impregnation on Nb-modified alumina using a Ni/Nb atom ratio of 2. Catalytic runs were performed at 235 ºC/ 45 bar for 30 h TOS, at 12.2 h−1 WHSV.All the catalysts showed high carbon yields to liquid products, mainly 1,2-propylene glycol and hydroxyacetone. The NiNb-SI catalyst, prepared through sequential impregnation of Nb and Ni, demonstrated the highest initial glycerol conversion rate (69.3%) and stability over 30 h TOS. Furthermore, it produced the highest carbon selectivity for propylene glycol at 56.7%. The catalytic performance of NiNb-SISi was also assessed under the same conditions with the addition of hydrogen, resulting in an enhanced capacity for dehydration-hydrogenation. However, glycerol conversion decreased. Post-reaction characterization revealed that catalyst deactivation was primarily caused by leaching, sintering and oxidation of Ni.

Nickel-containing catalysts for ethylene conversion to motor fuel components and light alkenes

Polyfunctional Ni-containing catalysts supported on the B2O3-Al2O3 and MoO3-Al2O3 were prepared by a sequential impregnation. They were evaluated in ethylene conversion to C5+ alkenes or propylene. The catalysts were characterized by X-ray diffraction, Fourier transformed infrared spectroscopy, Fourier transformed infrared spectroscopy of adsorbed CO, UV-VIS diffuse reflectance spectroscopy, temperature programmed reduction and temperature-programmed desorption of NH3. NiO/B2O3-Al2O3 samples containing Ni2+ cations chemically bonded to the acid support are the most effective catalysts for ethylene oligomerization. The NiO/MoO3-Al2O3 catalyst activity in the ethylene conversion to propylene is related with the presence of ethylene dimerization active sites, i.e. Ni2+ cations bonded to the support acidic sites, and active sites of metathesis in the form of monomolybdate species.

A biobased mixed metal oxide catalyst for biodiesel production from waste cooking oil: reaction conditions modeling, optimization and sensitivity analysis study

This study assessed the utilization of a heterogeneous catalyst derived from waste marble tiles and cow horn for waste cooking oil-derived biodiesel synthesis. The synthesized composite catalyst was prepared from waste marble tiles and cow horn through sequential calcination and wet impregnation. The catalyst and its precursors were characterized to analyze their composition, structural, and surface properties. The biodiesel production process was modeled and optimized via the response surface methodology (RSM) and artificial neural networks (ANN). Characterization of waste cooking oil revealed its suitability in biodiesel production. The catalyst had a surface area of 301.510 m2/g, while the pore volume and pore diameter were 0.165 cm3/g and 2.110 nm respectively, which contributed to the optimum biodiesel yield of 98% at a reaction time of 119.92 min, a catalyst concentration of 5.12 wt%, a reaction temperature of 74.86 °C, and methanol-to-oil ratio of 11.43:1. The catalyst was reusable for up to seven cycles while retaining significant activity. The optimized biodiesel sample had properties that met standards. RSM and ANN demonstrated adequate representation of the biodiesel yield as shown by their high R2 values although ANN was superior since it had higher R2 (0.9993) and adjusted R2 (0.9977) values. Global sensitivity analysis results showed reaction temperature as the most important input variable. This work has provided insights into the valorization of waste cooking oil for sustainable biodiesel production through heterogeneous catalysis.

Synthesis and evaluation of novel Cu-based adsorbent-containing catalysts for CO2 hydrogenation to methanol and value-added products

In this work, sequential incipient wetness impregnation method was used to synthesize Cu/Al2O3, Cu/Na2O/Al2O3 and Cu/CaO/Al2O3 catalysts in different compositions for CO2 conversion to value-added products. Synthesized catalysts were characterized using various analytical techniques and their performances for CO2 catalytic conversion were tested in a high-pressure packed bed reactor under reaction conditions of P = 60 bars, T = 300 °C, and H2/CO2 = 3. The obtained results revealed that the type of adsorbent had a significant impact on CO2 conversion, with CaO-containing catalyst being more efficient for methanol selectivity. Increased Cu content from 10 wt% to 30 wt% with fixed CaO content of 10 wt% resulted in a small increase in CO2 conversion where the highest CO2 conversion of 16.44% and the highest methanol selectivity (17.75%) were obtained for catalyst containing 20 wt% of copper. The best performing catalyst was further promoted using 0.5 wt% Rh promoter which improved both methanol selectivity and space time yield to 23.2% and 0.08 gMeOHgcat−1h−1, respectively. The comparative high performance of the Rh-promoted catalyst was attributed to smaller metal oxide particle size with uniform dispersion, presence of effective hydrogen spill over, moderate basic sites, surface defects and presence of induced copper species.