Surface Reaction Process Research Articles

Chemiresistive detection of xylene vapor using MOF-derived porous Co3O4 microrods activated by Mo6+ cations

Incorporation of high-valence cation into catalytic oxide (eg. Co3O4) is favorable for regulating the carrier concentration and creating more active centers for surface reaction process, thus promoting the sensing capability towards low reactive gas (eg. xylene). Herein, the metal-organic framework (MOF)-derived Mo-doped porous Co3O4 microrods are achieved through a simple solution method combing with a thermal method. The introduction of Mo6+ into Co3O4 matrix enhances the concentration of oxygen defects and Co3+, coupled with the specific surface area. As a result, the 5 at% Mo/Co3O4-based gas sensor sample exhibits a nice selectivity, clear response value (Rg/Ra=29.8 – 100 ppm), low concentration limit (0.5 ppm), and reliable stability to xylene vapor under a low working temperature (140 °C). Moreover, the possible reaction pathway (benzyl-benzaldehyde-benzoate-aromatic ester/anhydride) of xylene oxidation over this 5 at% Mo-doped Co3O4 microrod is proved by an in-situ DRIFTS analysis. Importantly, this optimized xylene-sensing capability is further discussed from the viewpoint of Mo-introducing effect into the porous Co3O4 microrods. This work further demonstrates a reliable approach of high valence cation-doped catalytic oxides to detect low reactive vapor.

Thiourea crystal growth kinetics, mechanism and process optimization during cooling crystallization

In the cooling crystallization process of thiourea, a significant issue is the excessively wide crystal size distribution (CSD) and the abundance of fine crystals. This investigation delves into the growth kinetics and mechanisms governing thiourea crystals during the cooling crystallization process. The fitting results indicate that the crystal growth rate coefficient, kg, falls within the range of 10–7 to 10–8 m·s–1. Moreover, with decreasing crystallization temperature, the growth process undergoes a transition from diffusion-controlled to surface reaction-controlled, with temperature primarily influencing the surface reaction process and having limited impact on the diffusion process. Comparing the crystal growth rate, G, and the diffusion-limited growth rate, Gd, at different temperatures, it is observed that the crystal growth process can be broadly divided into two stages. At temperatures above 25 °C, 1/qd approaches 1, indicating the predominance of diffusion control. Conversely, at temperatures below 25°C, 1/qd increases rapidly, signifying the dominance of surface reaction control. To address these findings, process optimization was conducted. During the high-temperature phase (35–25 °C), agitation was increased to reduce the limitations posed by bulk-phase diffusion in the crystallization process. In the low-temperature phase (25–15 °C), agitation was reduced to minimize crystal breakage. The optimized process resulted in a thiourea crystal product with a particle size distribution predominantly ranging from 0.7 to 0.9 mm, accounting for 84% of the total. This study provides valuable insights into resolving the issue of excessive fine crystals in the thiourea crystallization process.

Enhanced interfacial effect via acid theory with boosted photocatalytic performance of nitenpyram removal

Surface reaction is a prominent aspect that affects the efficiency of photocatalysis. In this work, acid theory was employed to facilitate the reaction dynamics and enhance the interfacial effect between photocatalysts and target molecules. The photocatalytic removal efficiency of NTP was 66 % for bare CdS in 50 min with apparent rate constants of 0.023 compare to 96 % with apparent rate constants of 0.065 for 5% Ce–CdS. The introduced Ce atom as bifunctional active site reduces the energy barrier of O2 adsorption, strengthens the interfacial effect and accelerates the electrons transfer, which could facilitate surface reaction process and boost the photocatalytic performance.

Evaluation of zirconia surfaces and shear bond strength after acid–etching with ultrasonic vibration

To evaluate the effect of surface reaction process after hydrofluoric (HF) acid etching using ultrasound and the shear bond strength (SBS) of resin cement to zirconia polycrystal (Y-TZP) ceramic. Y-TZP ceramic sheets were divided into rinsing group (Group P), ultrasonic cleaning group (Group C), and ultrasonic reaction + rinsing group (Group CP), and all the groups were treated for 5, 10, 20, 30, 40, 50, and 60 min, respectively. The surface morphology, elements distribution, roughness, and wettability of the ceramic sheets in each group were observed. The SBS of ceramic-resin bonding specimens was tested after immersion and after cooling-heating cycles, respectively. Octahedral and spiculate products were observed on the surface of Y-TZP that was etched with HF acid in Group P. The amount of these products increased over time. In contrast, only a few octahedral products remained on the surface of Y-TZP in Groups C and CP. Within the same reaction time, the surface reaction of the CP group was stronger than that of the other two groups, accompanied by a more uniform morphology. The shear force in Group C was the lowest, and the shear force reduction in Group CP was the least after cooling-heating cycling, with statistically significant differences (P< 0.05). After the reaction time exceeded 30 min, the shear force in each group decreased instead of increasing. Octahedral and spiculate acid etching products on the surface of HF acid-etched Y-TZP can enhance the bonding force of zirconia. Ultrasonic cleaning would drive the exfoliation of acid etching products from the sample surface, leading to the decrease of the bonding force. The acid etching with ultrasonic vibration can accelerate the HF acid etching process of Y-TZP ceramics, which is conducive to improving the bond strength to resin and durability.

Density functional theory study on the formation mechanism of CaClOH in municipal solid waste incineration fly ash.

Municipal solid waste incineration (MSWI) fly ash is defined as a kind of hazardous waste because of its high levels of multiple pollutants. The main component of MSWI fly ash is CaClOH, and the characteristics have not achieved consensus. And density functional theory (DFT) was used to calculate the formation process of CaClOH in this study, which mainly included HCl adsorption on CaO (0 0 1) surface and Ca(OH)2 (0 0 1) surface and the surface reaction process. The reaction mechanism was investigated. The results showed that the maximum adsorption energies of HCl on CaO and Ca(OH)2 surfaces reached - 195.17kJ/mol and - 83.48kJ/mol, respectively, representing strong chemisorption. The chemisorption process was shown as the adsorption of H atom on O site, and the adsorption capacity was reflected in the adsorption range of O site. The significant electron density overlap between O site and H atom meant that a new chemical bond formed, which made the adsorption structure stable. The adsorption energy of multi-HCl adsorption on the crystal surfaces was not proportional to the number of HCl molecule, indicating that the adsorption processes were influenced by each other. After surface reaction, the H-Cl bond was broken completely, and the structure of CaO and Ca(OH)2 changed to new structures. According to transition state (TS) search, the formation of CaClOH had a higher priority, easier than that of CaCl2, explaining the presence of CaClOH in fly ash. The study provides helpful information for the solidification treatment of fly ash.

Experimental Investigation and Modeling of Film Flow Corrosion

The paper focuses on the experimental investigation and mathematical modeling of the corrosion of steel when a film of water flows over its surface. The experimental monitoring of corrosion dynamics in the flowing film was carried out using a laboratory pilot model, exploited in such a way as to obtain data necessary to identify some characteristic parameters of the mathematical model of this problem. The mathematical model of the case takes into account the transfer of oxygen through the liquid film flowing on the surface of the corroding plate where the chemical surface processes characteristic of corrosion occur (dissolution of Fe, oxidation of Fe2+ to Fe3+, formation of surface deposit, etc.). Experimental measurements were used to identify the parameters of the mathematical model, especially the reaction constant of the Fe dissolution rate and the surface oxidation yield of Fe2+ to Fe3+. Calculation of the correlation coefficients for the apparent constant surface reaction rate and process factors showed that they correlate strongly and non-linearly with the Reynolds number (Re) of the film flow, with the cumulative flow duration, and with the cumulative standby time of the experiments. Using the dynamics of the resistance to the transfer of oxygen through the rust film and the dynamics of its thickness resulting from the specific flow of rust deposition, the apparent oxygen diffusion coefficient through the rust film formed on the plate was expressed.

Recyclable NiMnOx/NaF catalysts: Hydrogen generation via steam reforming of formaldehyde

In this paper, a low-cost and efficient NiMnOx/NaF catalyst that can be recycled for re-preparation was developed by sol–gel method for formaldehyde steam reforming to produce hydrogen, aiming at the high cost of commercial reforming catalyst and the difficulty of recycling after deactivation and abandonment. Results showed that the NiMnOx/NaF catalyst could efficiently steam reforming formaldehyde to produce hydrogen. Among them, the catalyst with 5 wt% NiMnOx had better hydrogen production performance, achieving 100% hydrogen yield, 100% formaldehyde conversion and 100% carbon balance from 500 to 600 ℃. Moreover, 5%-NiMnOx/NaF catalyst exhibited excellent stability at 500 ℃ for 28 h and the hydrogen production performance of the recycled catalyst was restored to the level of the initial fresh sample. Combining analysis of FE-SEM, N2 adsorption/desorption, XRD, H2-TPR, in situ DRIFTS, XPS, and DFT calculations, it was found that the surface micro-structure of the NaF carrier was dense, and the specific surface area of the NiMnOx/NaF catalyst was very small, breaking through the limitation of low specific surface area catalysts that cannot obtain high-quality catalytic activity. Its steam reforming of formaldehyde to produce hydrogen was a fast surface reaction process. Ni and Mn species combined with NaF to form the Na0.67Ni0.33Mn0.67O2 phase, and F atom had a strong induction effect on Ni atom, which was conducive to weakening the Ni-O bond, thus improving the low-temperature redox performance of Ni2+. In the process of reforming formaldehyde to produce hydrogen, the NiMnOx/NaF catalyst could quickly adsorb and activate formaldehyde and H2O molecules, and promoted the formation of formate intermediates through the adsorbed hydroxyl groups on the surface, and then rapidly produced H2 and CO2.

Direct Catalytic Oxidation of Low-Concentration Methane to Methanol in One Step on Ni-Promoted BiOCl Catalysts.

The direct oxidation of low-concentration methane (CH4) to methanol (CH3OH) is often regarded as the "holy grail". However, it still is very difficult and challenging to oxidize methane to methanol in one step. In this work, we present a new approach to directly oxidize CH4 to generate CH3OH in one step by doping non-noble metal Ni sites on bismuth oxychloride (BiOCl) equipped with high oxygen vacancies. Thereinto, the conversion rate of CH3OH can reach 39.07 μmol/(gcat·h) under 420 °C and flow conditions on the basis of O2 and H2O. The crystal morphology structure, physicochemical properties, metal dispersion, and surface adsorption capacity of Ni-BiOCl were explored, and the positive effect on the oxygen vacancy of the catalyst was proved, thus improving the catalytic performance. Furthermore, in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was also performed to study the surface adsorption and reaction process of methane to methanol in one step. Results demonstrate that the key to keep good activity lies in the oxygen vacancies of unsaturated Bi atoms, which can adsorb and active CH4 and to produce methyl groups and adsorbing hydroxyl groups in methane oxidation process. This study broadens the application of oxygen-deficient catalysts in the catalytic conversion of CH4 to CH3OH in one step, which provides a new perspective on the role of oxygen vacancies in improving the catalytic performance of methane oxidation.

On-Surface Synthesis of Self-Assembled Covalently Linked Wavy Chains with Site-Selective Conformational Switching.

Conformational arrangements in polymers on surfaces determine the overall shape as well as the potential properties. It is generally believed that conformational diversity leads to uncontrollable or disordered structures in on-surface synthesis. However, in this study, we obtain two well-ordered self-assembled covalently linked wavy chains with site-selective conformational switching via the Ullmann reaction of 1,2-bis(3-bromophenyl)ethane with multiple conformations on Ag(111). Two kinds of wavy chains exhibit distinct conformational arrangements, where chain I contains one repeating unit conformation of -cis-trans1-cis-trans1-cis-cis-trans1-, while the adjacent parallel parts in wavy chain II have two different conformational arrangements of -cis-cis-trans1- and -cis-cis-trans2-. Wavy chains coassemble with dissociated bromine atoms, suggesting that the Br···H-C interactions between Br atoms and molecular chains are crucial for the construction of ordered wavy chains. High-resolution scanning tunneling microscopy is employed to reveal the surface reaction process at the molecular scale. In depth growth mechanism analysis combined with density functional theory calculations unveils that the substrate also plays an important role in the fabrication of well-ordered wavy chains. The present work extends the surface reaction of conformational flexible precursors.

Simultaneous electrocatalytic removal of inorganic nitrogen compounds in groundwater: Modeling and mechanistic studies

The use of biological and chemical methods for the simultaneous removal of inorganic nitrogen compounds containing nitrate, ammonia, and nitrite in groundwater typically cannot achieve synchronous oxidation and reduction in an undivided reactor. In the present study, with the strict regulation of the oxidation reaction in the anode zone and reduction reaction in the cathode zone, simultaneous removal of nitrate, ammonia, and nitrite was achieved in an undivided electrochemical system. Our results indicated that ammonia and nitrite had been completely removed, and the concentration of nitrate was reduced to 8.58 mg N/L with initial nitrate, ammonia, and nitrite concentrations of 50.00, 10.00 and 5.00 mg N/L, respectively. Cyclic voltammetry (CV) and potentiostatic electrolysis revealed that the electrode surface reaction process, that is, nitrate, ammonia, and nitrite in the system, could be converted into nitrogen via ClO− generated from Cl− produced from the electrochlorination process during multiple cycle attenuation. Moreover, both CV and Density functional theory (DFT) calculations revealed the inhibitory effect of coexisting ammonia and nitrite on the electrochemical reduction of nitrate on the Cu cathode. This strategy opens a paradigm for the simultaneous efficient electrocatalytic removal of nitrate, nitrite, and ammonia in an undivided single reactor.

A promising catalytic solution of NO reduction by CO using g-C3N4/TiO2: A DFT study

The direct catalytic reduction of nitric oxide (NO) by carbon monoxide (CO) to form harmless N2 and CO2 is an ideal strategy to simultaneously remove both these hazardous gases. To investigate the feasibility of using graphitic carbon nitride/titanium dioxide (g-C3N4/TiO2) to catalyze the NO reduction by CO, we systematically explore the effect of the interfacial coupling between g-C3N4 and TiO2 on the photo-induced carrier separation, the light absorption, and the surface reaction for the NO reduction by using density functional theory. The g-C3N4/TiO2 is predicted to have a better photocatalytic activity for NO reduction than g-C3N4, due to the enhanced light absorption intensity and the accelerated separation of the photo-excited electron-hole pairs. By comparing the reaction routes on g-C3N4/TiO2 and g-C3N4, the results indicate that the introduction of TiO2 can keep the surface reaction process intact with the NO dissociation (N2O formation) being the rate-determining (crucial) step. Moreover, TiO2 can facilitate the desorption of NO reduction products, avoiding the deactivation of g-C3N4. This work shows that the composition of TiO2 into g-C3N4 provides a promising catalyst in NO reduction by CO.

Identifying the Role of the Local Charge Density on the Hydrogen Evolution Reaction of the Photoelectrode.

Understanding the role of surface charges in the catalytic reaction is of great importance to fundamental science in photoelectrochemistry (PEC). However, spatial heterogeneities of charge transfer sites and catalytic sites at the electrode/electrolyte interface obscures the surface reaction process. Herein, we quantified the relationship between the local catalytic current of the hydrogen evolution reaction (HER) and the surface charge density using operando spatially resolved photovoltage microscopy on the Pt/Ti array on the p-Si photoelectrode. We found that the Pt/Ti islands on the p-Si surface worked as the main charge collect areas but as the sole catalytic sites to drive the PEC hydrogen evolution. Based on the achievements of identifying the local photocurrent and photovoltage on a single Pt/Ti island, we found that the local HER current can be linearly regulated by the charge density at reactive sites by concurrently adjusting the bias potential and the spacings of the Pt/Ti islands. These results emphasize the significant impact of the surface charge density on the catalytic activity in photoelectrochemistry.

Tailored d-Band Facilitating in Fe Gradient Doping CuO Boosts Peroxymonosulfate Activation for High Efficiency Generation and Release of Singlet Oxygen.

In the field of heterogeneous catalysis, limitations of the surface reaction process inevitably make improving the catalytic efficiency to remove pollutants in water a major challenge. Here, we report a unique structure of Fe surface-gradient-doped CuO that improves the overall catalytic processes of adsorption, electron transfer, and desorption. Interestingly, gradient doping leads to an imbalanced charge distribution in the crystal structure, thereby promoting the adsorption and electron transport efficiency of peroxymonosulfate (PMS). The orbital hybridization of Fe also improves the electronic activity. More importantly, the occupied d-orbital distribution is closer to the lower energy level, which improves the desorption of the reaction intermediate (1O2). As a result, the production and desorption of 1O2 have been improved, resulting in excellent BPA degradation ability (kinetic rate increased by 67.3 times). Two-dimensional infrared correlation spectroscopy is used to better understand the doping process and catalytic mechanism of Fe-CuO. Fe-O changes before Cu-O and is more active. The Fe-required active sites, active species intensity, and kinetic reaction rates show a good correlation. This research provides a scientific basis for expanding the purification of toxic organic pollutants in complex water environments by heterogeneous catalytic oxidation.

Rapid Atmospheric Leaching of Chalcopyrite Using a Novel Reagent of Trichloroisocyanuric Acid

With the decrease in high-grade chalcopyrite resources, the copper extraction from low-grade chalcopyrite has attracted more and more attention. However, the kinetic rates of chalcopyrite leaching with traditional oxidants are usually very slow due to the formation of the passivation layer. In this study, a novel reagent of chlorinated oxidant, trichloroisocyanuric acid (TCCA), was used to leach chalcopyrite for the first time. The experimental results showed that when the initial oxidant concentration for TCCA was 0.054 mol·L−1, the leaching temperature was kept at 55 °C, and the pH of the pulp was controlled at 1, the oxidation efficiency of Cu can reach above 90% in less than 30 min. Various analyses of chalcopyrite mineral ore and its oxidized residues, such as chemical composition analysis, X-ray diffraction analysis, scanning electron microscopy analysis and X-ray photoelectron spectroscopy, were conducted, respectively. No obvious passivation layer was found on the chalcopyrite surface, though the sulfur product can also be generated during the leaching. Reaction kinetic analysis results showed that the different influence of surface reaction and diffusion process on the dissolution of chalcopyrite is little due to the fast leaching speed. After calculation, the activation energy of the whole leaching reaction is 9.06 kJ·mol−1, much lower than that in other reports. The mechanism was also proposed that TCCA was hydrolyzed in the solution to form hypochlorous acid, which is the strong oxidant, and cyanuric acid, which prevents the formation of a passivation layer. The processing in this study is expected to be applied as a novel method for atmospheric leaching of chalcopyrite.

Promoted H2 splitting on ZnO by pre-adsorbed formic acid

Activation of hydrogen on oxide surface is of both practical and fundamental importance for broad fields of syngas-based chemical industries as well as clean energy utilizations. Previously we found ZnO can catalyze the heterolysis of H2, which only occurs at low temperatures (<50 K) due to the quick kinetics of the reversed reaction. Here in this work, we demonstrate that the heterolytic adsorption of H2 can be significantly enhanced by pre-adsorbed formic acid molecules. The formic acid molecule can readily dissociate on the ZnO(10−10) surface and form strongly-bound formate and hydroxyl species, which induce charge accumulation at the nearest-neighbored Zn ions and initiate the heterolysis of H2 molecules as well as the growth of H-chain structure along the [0001] direction on the ZnO surface. With such stabilization effect of formic acid, the dissociative adsorption of H2 can be significantly raised up to 200 K under UHV conditions. These results strongly emphasize the important impact of co-adsorbates on the surface reaction process. Particularly, our findings may shed new light on the atomistic mechanisms for a variety of H2-involved reactions on oxide catalysts.

Effect of different supports on activity of Mn–Ce binary oxides catalysts for toluene combustion

The effects of support materials on catalytic performance were investigated in catalytic removal of toluene. And the Mn–Ce binary oxides as active components were supported on ZrO2, SiO2, γ-Al2O3 and TiO2 support materials. Many techniques, including X-ray diffraction (XRD), Brunauer–Emmett–Teller method (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and NH3-temperature-programmed desorption (NH3-TPD), were used to characterize physicochemical properties. Among the different catalysts, the MnCe/ZrO2 catalyst with the lowest specific surface area (39.7 m2/g) shows the best catalytic activity. In terms of toluene conversion, the activity order is as follows: MnCe/ZrO2 > MnCe/TiO2 ≈ MnCe/SiO2 > MnCe/Al2O3. The better performance of MnCe/ZrO2 should be attributed to the low-temperature reducibility, and abundant surface species (Mn4+ and lattice oxygen). And XPS and TPR results reveal that more surface abundant Mn and Ce elements generate good interaction in MnCe/ZrO2. The weak interaction between metal oxide and support also boosts the dispersion and complete reduction of MnCe oxides at low temperature. In addition, the in-situ DRIFTS results clarify that the carbonate species are main intermediates in MnCe/ZrO2 sample during surface reaction process.

Natural alumina/silica suspended particles in water to enhance ofloxacin degradation with UVA-H2O2 driven by surface chemistry

UV-H2O2 is the most widely used oxidizing system with established effectiveness and a high level of technical development for practical application. However, little attention was paid on the effect of suspended particles in natural water on organic contaminants removal via UV-H2O2 technique. In this study, this effect of suspended particles to enhance the contaminant degradation was explored using silica/alumina-based oxides (MCM-41 and Al@MCM-41) as the representative. The results showed that MCM-41 had no effect on OFX degradation compared with UV-H2O2. While the degradation efficiency and reaction rate were greatly enhanced at a pH range of 3.0–9.0 especially at acidic pH values (3.0–5.0) in the presence of Al@MCM-41. The probe experiments proved that OFX adsorption followed by surface reaction process played an important role to enhance the performance of UV-H2O2. Based on the characterization results, the positive effect of suspended particles was not related to their surface area and pore size distribution, but dependent on the chemical composition and surface acid-base property. The suspended particles can provide an active surface composed of acid and base sites. The base site can create a local basic micro-environment by producing more •OH et al. While the dissociated acid sites in Al@MCM-41 with a negative charged surface favor OFX adsorption and then reaction with produced ROS. Our findings suggest that the enhanced performance of UVA-H2O2 induced by suspended particles should be concerned.

Motivated surface reaction thermodynamics on the bismuth oxyhalides with lattice strain for enhanced photocatalytic NO oxidation

Understanding and establishing a specific relationship between modified structures and photocatalytic reaction process has a profound significance for designing catalysts with preferable activity. In this study, we have favorably synthesized the bismuth oxyhalides (BiOClxBr1-x, 0 ≤ x ≤ 1) photocatalysts by utilizing the ethylene glycol assisted solvothermal method and the calcination procedure for photocatalytic nitric oxide oxidation. By regulating the halogen proportion in anions layer, the lattice strain has been induced in the structure, specifically the tensile strain in c axis. By virtue of in situ DRIFTS and DFT calculation, we found that the optimized surface reaction thermodynamic process should be the main factors response for prominent enhanced photocatalytic activity, rather than the light absorption and separation of carriers. The bismuth oxyhalides with Cl/Br ratios of 3:1 (BiOClxBr1-x-3:1) possess the lowest thermodynamic energy barrier for photocatalytic nitric oxide oxidation reaction, whilst both associative and dissociative reaction process exist in the initial elementary reaction about oxygen reduction. Finally, we develop a feasible strategy to depress thermodynamic energy barriers via tuning the ratio of halogen in anions layer and bringing the lattice strain, as well build relationship between the adjusted structures and surface reaction process.

Hydrogen production from formaldehyde steam reforming using recyclable NiO/NaF catalyst

Harmless disposal of formaldehyde for hydrogen production is attractive in energy and environmental science. Herein, hydrogen production from formaldehyde steam reforming (FSR) using recyclable NiO/NaF was investigated, and the optimized 4 wt% catalyst exhibited 100% formaldehyde conversion, 104.9% H2 selectivity and excellent stability at 400 °C. The used catalysts can be easily recycled by water washing and pickling, and the activity of the regenerated catalyst is comparable to that of fresh one. We confirmed that FSR was a rapid surface reaction process, and the special contribution of NaF ensured the high activity of NiO/NaF with low specific surface areas. F ions in the carrier could activate the surface OH, which promoted adsorption and oxidation to reactants. Furthermore, the in situ DRIFTs study revealed that formate species (HCOO) was the key intermediate in formaldehyde steam reforming. Formaldehyde was first oxidized to HCOO and then decomposed into CO2 and H.

Hydrogen production from formaldehyde steam reforming using recyclable NiO/NaCl catalyst

The harmless treatment of formaldehyde and co-produce of hydrogen has drawn a lot of interest in the field of both energy and environmental science. Herein, NiO supported on NaCl (NiO/NaCl) was designed as catalyst to produce hydrogen via formaldehyde steam reforming (FSR). At 450 °C, the optimal 3 wt% NiO/NaCl catalyst had 102.8% H2 selectivity, close to 100% formaldehyde conversion and 48-hour stability. The used catalysts can be easily regenerated and recycled by washing with water and acid. The regenerated 3% NiO/NaCl catalyst had comparable catalytic performance as the fresh one. Since the specific surface area of the NiO/NaCl catalysts was as low as 1.3 m2·g−1, the FSR reaction should be a fast surface reaction process. The reaction was further investigated by in situ DRIFTs, H2-TPR and XPS. The excellent catalytic activity can be attributed to the interaction between the NiO active component and NaCl support, which can activate the surface hydroxyl groups and promote the adsorption and oxidation of the reactants.