Hydrogenation Of Nitrate Research Articles

Improved Nitrate-to-Ammonia Electrocatalysis through Hydrogen Poisoning Effects.

Electrochemical conversion from nitrate to ammonia is a key step in sustainable ammonia production. However, it suffers from low productive efficiency or high energy consumption due to a lack of desired electrocatalysts. Here we report nickel cobalt phosphide (NiCoP) catalysts for nitrate-to-ammonia electrocatalysis that display a record-high catalytic current density of -702±7 mA cm-2, ammonia production rate of 5415±26 mmol gcat-1 h-1 and Faraday efficiency of 99.7±0.2 % at -0.3 V vs. RHE, affording the estimated energy consumption as low as 22.7 kWh kgammonia-1. Theoretical and experimental results reveal that these catalysts benefit from hydrogen poisoning effects under low overpotentials, which leave behind catalytically inert adsorbed hydrogen species (HI*) at Co-hollow sites and thereupon enable ideally reactive HII* at secondary Co-P sites. The dimerization between HI* and HII* for H2 evolution is blocked due to the catalytic inertia of HI* thereby the HII* drives nitrate hydrogenation timely. With these catalysts, the continuous ammonia production is further shown in an electrolyser with a real energy consumption of 18.9 kWh kgammonia-1.

Unveiling Ionized Interfacial Water-Induced Localized H* Enrichment for Electrocatalytic Nitrate Reduction.

Electrocatalytic nitrate reduction reaction (NO3RR) is a process that requires the participation of eight electrons and nine protons. The regulation of active hydrogen (H*) supply and a deep understanding of related processes are necessary for improving the ammonia yield rate and Faradaic efficiency (FE). Herein, we synthesized a series of atomically precise copper-halide clusters Cu2X2(BINAP)2 (X = Cl, Br, I), among which the Cu2Cl2(BINAP)2 cluster shows the optimal ammonia FE of 94.0% and an ammonia yield rate of 373 μmol h-1 cm-2. In situ experiments and theoretical calculations reveal that halogen atoms, especially Cl in Cu2Cl2(BIANP)2, can significantly affect the distance of alkali metal-ionized water on the catalyst surface, which can promote the water dissociation to enhance the localized H* enrichment for the continues hydrogenation of nitrate to ammonia. This work explains the role of H* in the hydrogenation process of NO3RR and the importance of localized H* enrichment strategy for improving the FEs.

Sustainable catalytic hydrogenation of high concentration nitrate to ammonia over Ruthenium-based catalysts

Elevated nitrate levels in natural water bodies significantly disrupt the global nitrogen cycle and pose a substantial environmental and human health risk. This study investigates the selective conversion of nitrate to ammonia via catalytic hydrogenation. This highly efficient and selective process offers a sustainable alternative to traditional ammonia production methods while simultaneously addressing nitrate pollution. Ruthenium (Ru) catalysts supported on ceria (CeO2), titania (TiO2), and tin dioxide (SnO2) were synthesized using a simple impregnation method, incorporating oxygen vacancies and low Palladium (Pd) loadings (0.25–0.5 wt%) to enhance catalytic performance. Ru-Pd/CeO2 exhibited superior activity and selectivity, maintaining near 100 % ammonia selectivity across various nitrate concentrations. At 75 °C, complete conversion of 2000 ppm nitrate to ammonia was achieved within 80 min using Ru-Pd/CeO2, and the yield of ammonia can reach up to 16440 mg•h−1•gRu-1. Subsequent ammonia enrichment through evaporation yielded pure ammonia solutions up to 3.6 wt%. Characterization and theoretical calculations suggest that abundant oxygen vacancies on the CeO2 surface and efficient hydrogen spillover from Pd nanoparticles synergistically contribute to the Ru-Pd/CeO2 catalyst’s superior performance. The catalyst exhibited excellent stability and reusability, maintaining high activity and selectivity over four cycles. This research presents a promising strategy for addressing nitrate pollution in water bodies while offering a sustainable and environmentally friendly route for ammonia synthesis. The findings of this study lay the foundation for further advancing and potentially implementing catalytic hydrogenation technology for nitrate pollution remediation and ammonia synthesis.

Hydrogen Spillover Mechanism at the Metal–Metal Interface in Electrocatalytic Hydrogenation

AbstractHydrogen spillover in metal‐supported catalysts can largely enhance electrocatalytic hydrogenation performance and reduce energy consumption. However, its fundamental mechanism, especially at the metal–metal interface, remains further explored, impeding relevant catalyst design. Here, we theoretically profile that a large free energy difference in hydrogen adsorption on two different metals (|ΔGH‐metal(i)−ΔGH‐metal(ii)|) induces a high kinetic barrier to hydrogen spillover between the metals. Minimizing the difference in their d‐band centers (Δϵd) should reduce |ΔGH‐metal(i)−ΔGH‐metal(ii)|, lowering the kinetic barrier to hydrogen spillover for improved electrocatalytic hydrogenation. We demonstrated this concept using copper‐supported ruthenium–platinum alloys with the smallest Δϵd, which delivered record high electrocatalytic nitrate hydrogenation performance, with ammonia production rate of 3.45±0.12 mmol h−1 cm−2 and Faraday efficiency of 99.8±0.2 %, at low energy consumption of 21.4 kWh kgamm−1. Using these catalysts, we further achieve continuous ammonia and formic acid production with a record high‐profit space.

Hydrogen Spillover Mechanism at the Metal-Metal Interface in Electrocatalytic Hydrogenation.

Hydrogen spillover in metal-supported catalysts can largely enhance electrocatalytic hydrogenation performance and reduce energy consumption. However, its fundamental mechanism, especially at the metal-metal interface, remains further explored, impeding relevant catalyst design. Here, we theoretically profile that a large free energy difference in hydrogen adsorption on two different metals (|ΔGH-metal(i)-ΔGH-metal(ii)|) induces a high kinetic barrier to hydrogen spillover between the metals. Minimizing the difference in their d-band centers (Δϵd) should reduce |ΔGH-metal(i)-ΔGH-metal(ii)|, lowering the kinetic barrier to hydrogen spillover for improved electrocatalytic hydrogenation. We demonstrated this concept using copper-supported ruthenium-platinum alloys with the smallest Δϵd, which delivered record high electrocatalytic nitrate hydrogenation performance, with ammonia production rate of 3.45±0.12 mmol h-1 cm-2 and Faraday efficiency of 99.8±0.2 %, at low energy consumption of 21.4 kWh kgamm -1. Using these catalysts, we further achieve continuous ammonia and formic acid production with a record high-profit space.

Unveiling the Reaction Mechanism of Nitrate Reduction to Ammonia Over Cobalt-Based Electrocatalysts.

Electrocatalytic reduction of nitrate to ammonia (NRA) has emerged as an alternative strategy for sewage treatment and ammonia generation. Despite excellent performances having been achieved over cobalt-based electrocatalysts, the reaction mechanism as well as veritable active species across a wide potential range are still full of controversy. Here, we adopt CoP, Co, and Co3O4 as model materials to solve these issues. CoP evolves into a core@shell structured CoP@Co before NRA. For CoP@Co and Co catalysts, a three-step relay mechanism is carried out over superficial dynamical Coδ+ active species under low overpotential, while a continuous hydrogenation mechanism from nitrate to ammonia is unveiled over superficial Co species under high overpotential. In comparison, Co3O4 species are stable and steadily catalyze nitrate hydrogenation to ammonia across a wide potential range. As a result, CoP@Co and Co exhibit much higher NRA activity than Co3O4 especially under a low overpotential. Moreover, the NRA performance of CoP@Co is higher than Co although they experience the same reaction mechanism. A series of characterizations clarify the reason for performance enhancement highlighting that CoP core donates abundant electrons to superficial active species, leading to the generation of more active hydrogen for the reduction of nitrogen-containing intermediates.

An electrochemical approach for designing thermochemical bimetallic nitrate hydrogenation catalysts

An electrochemical approach for designing thermochemical bimetallic nitrate hydrogenation catalysts

Efficiently unbiased solar-to-ammonia conversion by photoelectrochemical Cu/C/Si-TiO2 tandems

Photoelectrochemical nitrate reduction reaction (PEC NO3RR) is of interest as a promising route to directly realizing the solar-to-ammonia (NH3) conversion but the limited efficiency and high applied bias voltage hamper its commercial prospects. Here, we report a bias-free photoelectrochemical cell for PEC NO3RR in aqueous conditions, achieving a substantial NH3 yield rate of 13.1 μmol·h−1·cm−2, high faradaic efficiency of 93.8%, and recorded solar-to-NH3 conversion of ∼1.5% under 1 sun illumination. A hierarchical-structured Si-based photocathode with Cu+/Cu2+-containing Cu nanoparticles cocatalysts achieves a highly efficient PEC NO3RR with NH3 yield rate of 115.3 μmol·h−1·cm−2 in a three-electrode system. Integrating operando characterizations and systematic PEC measurements, the formation of Lewis acid sites on Cu nanoparticles by accepting the photoinduced electrons is the dominant factor for facilitating the absorption and hydrogenation of nitrate. This work will guide the development of a robust, high-performance, and unbiased PEC device for sustainable solar-to-NH3/other fuels conversion.

Nitrate and nitroarene hydrogenations catalyzed by alkaline-earth nickel phosphide clathrates.

The alkaline-earth-containing nickel phosphide clathrates AeNi2P4 (Ae = Ba, Sr) are investigated as catalysts for the reduction of nitrate or nitroarenes in aqueous or ethanolic solution, respectively. While AeNi2P4 clathrates are inactive in their bulk polycrystalline form, they become active in nitrate hydrogenation after size reduction by either grinding or ball milling. However, while the clathrate structure remains intact after manual grinding, ball milling is of limited use as it results in significant clathrate degradation. Ground AeNi2P4 catalysts are also active in nitroarene hydrogenation. Condensation products such as azoxy- and azo-benzenes form early (4 h) but anilines accumulate after long reaction times (24 h). Unexpectedly, BaNi2P4 partially devinylates nitrostyrene to nitrobenzene. Overall, BaNi2P4 is more active than SrNi2P4 in both nitrate and nitroarene hydrogenation. These results showcase the potential utility of clathrates in a growing number of catalytic transformations.

Recovery of valuable metals from spent lithium-ion batteries through an ecofriendly catalytic approach

The rapid growth of lithium-ion batteries (LIBs) used in electric vehicles is amplifying the importance of recycling valuable materials from spent batteries. Current recycling technologies utilize extractive metallurgical processes to recover metals, particularly from cathode materials. However, pyrometallurgy requires high temperatures for smelting, while hydrometallurgy relies on toxic chemical reagents for leaching. Here, we present a catalytic strategy designed to overcome the energy and environmental challenges associated with metallurgical processes. The extraction reaction is conducted using an HxRuO2 catalyst in the presence of HNO3, H2, and CO2. Extraction is achieved through the selective hydrogenation of nitrate to ammonia, followed by the carbonation of leached metal species. The catalytic process successfully achieves nearly complete recovery of Co and Li as carbonates from LiCoO2. Furthermore, we demonstrate the versatility of this catalytic approach in recovering metals from various cathode materials, including spent LIBs. This newly developed one-pot method offers a promising industrial process for recycling valuable metals from spent batteries in an atom-efficient and environmentally friendly manner, without generating waste.

Critical Roles of Chalcogenide Anion on Strengthening Stability of Ni2Mo6Te8 for Almost Exclusive Electrocatalysts Nitrate to Ammonia Conversion

AbstractElectrochemical hydrogenation of nitrate to ammonia using renewable electricity is a promising route for sustainability but lacks catalysts that can deliver balanced selectivity, activity, and durability. Here, a new family of noble metal‐free and high‐performing Chevrel phase Ni2Mo6T8 (T = S, Se, and Te) catalysts that have similar structural and textural properties and differ presumably only in chalcogenide anion is systematically studied. The side‐by‐side comparisons allow the uncovering of the critical roles of chalcogenide anions in impacting kinetic activities and long‐term durability. The incorporation of anions with larger size and smaller electronegativity from sulfide to selenide and telluride invokes stronger inhibition of the otherwise competing hydrogen evolution reaction (HER) and steers the hydrogenation toward the selective formation of ammonia, thus improving both Faradic selectivity and the turnover frequency to high levels of 99.4% and 21.5 s−1, respectively, on the Ni2Mo6Te8 catalyst. More significantly, the bulkier anion in the Ni2Mo6T8 catalyst kinetically inhibited the intercalation of electrolyte cations, a major degradation mechanism in the catalyst family examined here and delivered several times improved durability. Therefore, this study introduces novel active motifs for selective nitrate reduction and provides insights into the catalyst degradation mechanism and practical ways to improve durability.

Pd/Cu bimetallic nano-catalyst supported on anion exchange resin (A520E) for nitrate removal from water: High property and stability

High nitrate concentration in water can lead to eutrophication and the disruption of healthy aquatic ecosystems. Additionally, in the human digestive system, it has the potential to be reduced to nitrite, which can be damaging to people's physical health. Catalytic hydrogenation of nitrate is one of the strategies for removing nitrate from water. Using A520E resin as support, we prepared Pd/Cu nano-catalyst (Pd/Cu@A520E) according to a liquid phase reduction method. A520E could improve the transfer process of nitrate in the solution to the activity sites of Pd/Cu nanoparticles, thus increase the reaction rate of nitrate reduction. Pd/Cu bimetallic nano-particles were evenly distributed on/in the resin with a size range from 2 nm to 10 nm. The External Circulating System equipped with Venturi tube (ECSV) was designed to improve the utilization efficiency of H2 in both batch tests and long-term continuous-flow tests. Nearly 100% of nitrate removal efficiency and above 90% of N2 selectivity were achieved in both batch tests and continuous-flow tests. Coexisting Cl− and SO42− at 300 mg/L showed little impact on the property of Pd/Cu@A520E. Pd/Cu@A520E also showed high nitrate removal property and stability in continuous-flow tests of more than 800 h. NO3− was adsorbed onto the active sites (functional groups and Pd/Cu particle sites), meanwhile H2 was adsorbed onto the active sites of Pd/Cu@A520E to form Pd [H]. Then the adsorbed NO3− was reduced into N2 (main product) or NH4+ by Pd [H]. In addition, Pd/Cu@A520E showed high nitrate removal property from municipal waste water.

Catalytic Hydrogenation of Nitrate over Immobilized Nanocatalysts in a Multi-Phase Continuous Reaction System: System Performance, Characterization and Optimization

Nitrate catalytic reduction in a continuous system was studied in the presence of Pd-Cu macrostructured catalysts synthesized through a novel washcoating methodology of the pre-formed bimetallic powder catalyst. The present work aims to understand the behavior of the macrostructured bimetallic catalyst in the presence of different reaction conditions in order to achieve the design of an optimized facility that can produce the best catalytic results: maximum NO3− conversion with enhanced N2 selectivity. The residence time of the inlet solution and the catalyst concentration in the reactor proved to be the parameters that most influenced the conversion and selectivity due to the important role that these parameters play in the hydrodynamic conditions of the reactor. A higher loading of catalyst and lower inlet flow rates allow promoting a higher contact time between the three phases that participate in the reaction (G-L-S). The most efficient reaction conditions (three pieces of the macrostructured catalyst, liquid flow rate of 10 mL min−1, and a total gas flow rate of 200 Ncm3 min−1 (1:1 H2:CO2)) allowed obtaining an NO3− conversion of 51% with a corresponding N2 selectivity of 23%. Also, the conversion results strongly depended on the total gas flow rate used during the reaction since this assists the mixing between the three phases and promotes a greater contact that will contribute to enhanced catalytic results.

Interfacial Engineering of Bimetallic Ni/Co-MOFs with H-Substituted Graphdiyne for Ammonia Electrosynthesis from Nitrate

The electrochemical synthesis of ammonia is highly dependent on the coupling reaction between nitrate and water, for which an electrocatalyst with a multifunctional interface is anticipated to promote the deoxygenation and hydrogenation of nitrate with water. Herein, by engineering the surface of bimetallic Ni/Co-MOFs (NiCoBDC) with hydrogen-substituted graphdiyne (HsGDY), a hybrid nanoarray of NiCoBDC@HsGDY with a multifunctional interface has been achieved toward scale-up of the nitrate-to-ammonia conversion. On the one hand, a partial electron transfers from Ni2+ to the coordinatively unsaturated Co2+ on the surface of NiCoBDC, which not only promotes the deoxygenation of *NO3 on Co2+ but also activates the water-dissociation to *H on Ni2+. On the other hand, the conformal coated HsGDY facilitates both electrons and NO3- ions gathering on the interface between NiCoBDC and HsGDY, which moves forward the rate-determining step from the deoxygenation of *NO3 to the hydrogenation of *N with both *H on Ni2+ and *H2O on Co2+. As a result, such a NiCoBDC@HsGDY nanoarray delivers high NH3 yield rates with Faradaic efficiency above 90% over both wide potential and pH windows. When assembled into a galvanic Zn-NO3- battery, a power density of 3.66 mW cm-2 is achieved, suggesting its potential in the area of aqueous Zn-based batteries.

Comparing methods to deposit Pd-In catalysts on hydrogen-permeable hollow-fiber membranes for nitrate reduction

Catalytic hydrogenation of nitrate in water has been studied primarily using nanoparticle slurries with constant hydrogen-gas (H2) bubbling. Such slurry reactors are impractical in full-scale water treatment applications because 1) unattached catalysts are difficult to be recycled/reused and 2) gas bubbling is inefficient for delivering H2. Membrane Catalyst-film Reactors (MCfR) resolve these limitations by depositing nanocatalysts on the exterior of gas-permeable hollow-fiber membranes that deliver H2 directly to the catalyst-film. The goal of this study was to compare the technical feasibility and benefits of various methods for attaching bimetallic palladium/indium (Pd/In) nanocatalysts for nitrate reduction in water, and subsequently select the most effective method. Four Pd/In deposition methods were evaluated for effectiveness in achieving durable nanocatalyst immobilization on the membranes and repeatable nitrate-reduction activity: (1) In-Situ MCfR-H2, (2) In-Situ Flask-Synthesis, (3) Ex-Situ Aerosol Impaction-Driven Assembly, and (4) Ex-Situ Electrostatic. Although all four deposition methods achieved catalyst-films that reduced nitrate in solution (≥ 1.1 min−1gPd−1), three deposition methods resulted in significant palladium loss (>29%) and an accompanying decline in nitrate reactivity over time. In contrast, the In-Situ MCfR-H2 deposition method had negligible Pd loss and remained active for nitrate reduction over multiple operational cycles. Therefore, In-Situ MCfR-H2 emerged as the superior deposition method and can be utilized to optimize catalyst attachment, nitrate-reduction, and N2 selectivity in future studies with more complex water matrices, longer treatment cycles, and larger reactors.

Electrocatalytic Hydrogenation Boosts Reduction of Nitrate to Ammonia over Single-Atom Cu with Cu(I)-N3C1 Sites.

The conversion of nitrate to ammonia can serve two important functions: mitigating nitrate pollution and offering a low energy intensity pathway for ammonia synthesis. Conventional ammonia synthesis from electrocatalytic nitrate reduction reactions (NO3RR) is often impeded by incomplete nitrate conversion, sluggish kinetics, and the competition of hydrogen evolution reactions. Herein, atomic Cu sites anchored on micro-/mesoporous nitrogen-doped carbon (Cu MNC) with fine-tuned hydrophilicity, micro-/mesoporous channels, and abundant Cu(I) sites were synthesized for selective nitrate reduction to ammonia, achieving ambient temperature and pressure hydrogenation of nitrate. Laboratory experiments demonstrated that the catalyst has an ammonia yield rate per active site of 5466 mmol gCu-1 h-1 and transformed 94.8% nitrate in wastewater containing 100 mg-N L-1 to near drinking water standard (MCL of 5 mg-N L-1) at -0.64 V vs RHE. Extended X-ray absorption fine structure (EXAFS) and theoretical calculations showed that the coordination environment of Cu(I) sites (Cu(I)-N3C1) localizes the charge around the central Cu atoms and adsorbs *NO3 and *H onto neighboring Cu and C sites with balanced adsorption energy. The Cu(I)-N3C1 moieties reduce the activation energy of rate-limiting steps (*HNO3 → *NO2, *NH2 → *NH3) compared with conventional Cu(II)-N4 and lead to a thermodynamically favorable process to NH3. The as-prepared electrocatalytic cell can run continuously for 84 h (14 cycles) and produce 21.7 mgNH3 with only 5.64 × 10-3 kWh energy consumption, suitable for decentralized nitrate removal and ammonia synthesis from nitrate-containing wastewater.

Water denitration over titania-supported Pt and Cu by combined photocatalytic and catalytic processes: Implications for hydrogen generation properties in a photocatalytic system

The present work provides a new approach to the water denitration process and a facile strategy of catalyst preparation for the efficient hydrogen generation. The main focus of the research reported here was nitrate removal from aqueous solutions and simultaneous hydrogen generation under UV-Vis-light irradiation. This is a very important aspect in case of practical applications, eliminating the external source of hydrogen. Aiming to get a deeper understanding on the role of surface structures (size and shape of nanoparticles) towards the reduction mechanism and to establish basic principles for an efficient process, Pt-Cu/TiO2 and Pt-Cu/TiO2 modified with well-defined Pt nanoparticles were employed. The synthesized materials were characterized using various physicochemical techniques and tested comparatively for: (i) nitrate catalytic reduction by hydrogen (dark reaction) and (ii) nitrate photocatalytic reduction by in-situ generated solar hydrogen. In order to enhance overall denitration reaction by combined photocatalytic and catalytic processes, photo-generated charges and in-situ generated H2 as reducing agent were used. Improvement of catalytic performances of nitrate hydrogenation reaction (~100% NO3¯ conversion) related to intimate contact between Pt and Cu was obtained. The in-situ generated H2 by water splitting over the studied catalysts reduces efficiently NO3¯ ions. Enhanced photocatalytic activity toward solar H2 production by deposited well-defined Pt nanoparticles (~10 nm) was achieved. In order to make possible decontamination of polluted waters using in-situ generated H2 under light exposure, the future optimization of such photo-catalytic systems looks promising.

Catalytic Hydrogenation of Nitrate Over Immobilized Nanocatalysts in a Multi-Phase Continuous Reaction System: System Performance and Optimization

Catalytic Hydrogenation of Nitrate Over Immobilized Nanocatalysts in a Multi-Phase Continuous Reaction System: System Performance and Optimization

A comparative evaluation of cetane enhancing techniques for improving the smoke, NOx and BSFC trade-off in an automotive diesel engine

The cetane number of a fuel strongly influences the combustion parameters and the emission characteristics of a diesel engine. In the case of biodiesel, the presence of polyunsaturated fatty acid methyl ester lowers the cetane number and leads to the decrement in ignition quality. This study investigates the potentiality of two different cetane enhancing techniques, viz. partial hydrogenation and addition of 2-Ethylhexyl nitrate (EHN) to improve the combustion quality of a diesel–biodiesel (B20) blend without hindering the emissions trade-off. The karanja biodiesel used here is exposed to partial hydrogenation in an autoclave reactor and the change in fuel composition is analyzed with gas chromatography. 2-Ethylhexyl nitrate (EHN) is chosen as the cetane enhancer with a concentration of 2000 ppm blended in B20. The NOx, smoke, and brake specific fuel consumption trade-off are quantified for diesel, B20, partially hydrogenated biodiesel blend (HB20), and EHN blended (B20 + EHN) fuels. An improvement in trade-off is observed with the use of modified B20 fuels at mid-range engine loads; however, the base diesel outperformed B20 and its modified forms at full load operations. Overall, the partial hydrogenation is proven to be a more beneficial method to improve the biodiesel trade-off characteristics than the addition of EHN.

Separation and hydrogenation of nitrate ions by micro-scale capacitive-faradaic fuel cells (CFFCs)

A new electrochemical process is proposed for a zero-discharge removal of nitrate ions from water. The process utilizes micro-scale capacitive-faradaic fuel cells (CFFC) made of activated carbon particles loaded with a Pt-Cu catalyst capable of oxygen reduction, hydrogen oxidation and nitrate hydrogenation reactions. Every CFFC comprises capacitive activated carbon electrode and faradaic Pt electrode. Oxygen reduction on Pt results in electrons’ deficiency in activated carbon which is equilibrated by an adsorption of nitrate ions from the treated water. Once the CFFCs are saturated with NO3− they must be regenerated. To repel NO3− ions into the regenerant solution the dissolved H2 is oxidized on Pt electrode of the CFFC. The accumulation of electrons in capacitive activated carbon electrode results in release of NO3− ions. Simultaneously the nitrate ions are reduced by the H2 gas on the Pt-Cu catalyst of the CFFC.Operation of CFFCs with 5%Pt-1%Cu catalyst resulted in highly effective separation and hydrogenation of nitrate ions into the N2 gas and ammonia. The adsorption density for nitrate ions was 0.175 meq/g_carbon. Selectivity for N2 gas was ≈ 55%. Further studies are required to decrease costs of CFFCs and to increase the N2 selectivity of the hydrogenation step.