Heterogeneous Reduction Reactions Research Articles

Microscopic Mechanism for Further NO Heterogeneous Reduction by Potassium-Doped Biochar: A DFT Study.

Biomass reburning is an efficient and low-cost way to control nitric oxide (NO), and the abundant potassium (K) element in biomass affects the heterogeneous reaction between NO and biochar. Due to the incomplete simulation of the NO heterogeneous reduction reaction pathway at the molecular level and the unclear catalytic effect of K element in biochar, further research is needed on the possible next reaction and the influencing mechanism of the element. After the products of the existing reaction pathways are referenced, two reasonably simplified biochar structural models are selected as the basic reactants to study the microscopic mechanism for further NO heterogeneous reduction on the biochar surface before and after doping with the K atom based on density functional theory. In studying the two further NO heterogeneous reduction reaction pathways, we find that the carbon monoxide (CO) molecule fragment protrudes from the surface of biochar models with the desorption of N2 at the TS4 transition state, and the two edge types of biochar product models obtained by simulation calculation are Klein edge and ac56 edge observed in the experiment. In studying the catalytic effect of potassium in biochar, we find that the presence of K increases the heat release of adsorption of NO molecules, reduces the energy barrier of the rate-determining step in the nitrogen (N2) generation and desorption process (by 50.88 and 69.97%), and hinders the CO molecule from desorbing from the biochar model surface. Thermodynamic and kinetic analyses also confirm its influence. The study proves that the heterogeneous reduction reaction of four NO molecules on the surface of biochar completes the whole reaction process and provides a basic theoretical basis for the emission of nitrogen oxides (NOx) during biomass reburning.

Experimental and Simulation Study on Ultra-Low NOx Emissions of Anthracite by Preheated Combustion

ABSTRACT In this study, the ultra-low NOx emission of anthracite was achieved by the preheated combustion technology. Meanwhile, the preheated combustion model was established using Aspen Plus. High-temperature preheating (above 950°C) improved the conversion process from fuel-nitrogen to N2 and precursor of NOx, which involved the cracking of N-5 and N-6. The conversion rate from fuel-nitrogen to N2 was 81.88%. In addition, heterogeneous reduction reaction of NOx was the critical conversion path of fuel-nitrogen for the ultra-low NOx emission during the combustion. The conversion rate from NOx to N2 was 0.43%. The average NOx emission of tail flue gas was 40.77 mg/m3 and 46.15 mg/m3 (@6%O2) for Jincheng anthracite and Yangquan anthracite, respectively. The simulation results showed that the preheated combustion model demonstrated precise prediction capabilities for containing-nitrogen gas emission. The maximum error of NOx emission and N2 concentration were 7.71% and 3.37%, respectively. The simulation and experimental results could be mutually verified.

Refreshing the liquid-gas reaction interface to provoke the zincothermic reduction of SiCl4 to prepare lithium-storage nano silicon

Many heterogeneous reduction reactions are hampered by the generated intermediate products located at the interface of reactants, resulting in reducing the reaction area or slowing down the mass transfer and thereby shutting off or slowing down the reaction. Thus, removing the unwanted intermediate products from the reaction interface is key to enabling a rapid and sufficient reduction rate and rationally mediating the product sizes and structures. Herein, we employ solid NaCl to absorb the intermediate molten ZnCl2 generated at the liquid Zn-SiCl4 gas interface, making the reaction happen continuously and sufficiently at a relatively low temperature of below 450 °C. In addition to refreshing the reaction interface, NaCl acts as a buffer to absorb the reaction heat, ensuring the production of hollow Si inherited from the spherical liquid Zn template. As a result, the yield of Si reaches over 95% within 2 h and the Si particle size is below 200 nm. Further, the obtained Si anode has an initial Coulombic efficiency of 86.7% and delivers a capacity of 1580 mAh g−1 at 3 A g−1 after 350 cycles with a capacity retention of 90.6%. Overall, this paper provides an effective strategy for engineering the reaction interface and revalorizing waste SiCl4 for making Li-storage Si anodes.

Effect of iron on heterogeneous reduction reaction of NO by char: A combined experimental and theoretical study

NOx production during coal combustion can be minimized by using the heterogeneous reduction reaction of NO on char. Here, coal-derived char was loaded with different amounts of Fe for heterogeneous reduction of NO at 1300°C in a one-dimensional tube furnace. The effects of Fe loading on the reaction was investigated for the first time. Meanwhile, theoretical calculations based on the wave function theory and density functional theory were carried out to explore the reaction steps at the molecular level. Two reaction pathways were identified involving different chemisorption sites. The catalytic mechanism of Fe in the entire NO reduction process was revealed, and thermodynamic and kinetic analyses were carried out based on the theoretical results. Overall, the NO reduction rate was greatly enhanced when the char contained Fe. At a FeCl3 loading of 0.4 wt%, the NO reduction rate reached the maximum and was 18.8% higher than that of the demineralized char. The catalytic mechanism of Fe could be attributed to the following aspects: creation of more new active sites for the chemisorption of NO by the destruction of conjugated π-bonds, reduction in the energy barrier of the rate-determining step, and facilitation of N–N bond formation and N2 desorption from the char surface. According to the thermodynamic and kinetic calculations, the introduction of Fe increased the upper limit and rate of the heterogeneous reduction reaction of NO.

Experimental study on effects of air-staged strategy and NH3 co-firing ratios on NO formation characteristics in ammonia/coal co-firing process

Ammonia/coal co-firing in coal-fired power plants is an effective and promising route to achieve CO2 reduction. This paper studies ammonia/coal co-firing in a 45 kW wall-temperature controlled staged combustion furnace employing overall air-staged combustion technology to meet the goal of low carbon and low NOx emissions. The effect of different burnout air addition positions and combustion environmental temperatures on the NO emissions, as well as the CO and H2S release characteristics of ammonia/coal co-firing was studied for ammonia co-firing ratios ranging from 0 % to 100 % (calorific value), with bituminous coal as the experimental object. To offer a qualitative overview of the experimental results, chemical reaction kinetic calculations were performed. The position of the burnout air addition has significant effects on the ammonia/coal co-firing products. The further the burnout air addition position is from the burner outlet, the lower the NO emission. When the distance is too great, however, the improvement in NO reduction efficiency is limited, which might have a negative impact on combustion efficiency. At 1300 °C, the NO emission concentration is substantially higher due to the deterioration of SNCR (selective non-catalytic reduction) capabilities of NH3 at high temperatures. High temperatures also reduce coal char production, which results in less heterogeneous reduction reactions on char surface. Based on experimental results and chemical kinetic calculations, the release patterns and mechanisms of combustion products during ammonia/coal co-firing under various air-staged strategies were explored in this work, presenting a promising technically achievable solution for reducing CO2 and NOx emissions from the coal-fired power plants.

Mechanism on the effect of sodium on the heterogeneous reduction reaction of NO by Char(N)

Sodium in high alkali coal promotes the heterogeneous reduction of NO in nitrogen-containing char. In order to deeply understand the mechanism of the effect of sodium on the reaction, two edge models, armchair and zigzag were employed to investigate the reaction paths before and after sodium doping, based on density function theory. It was found that after the addition of sodium, the reaction energy barriers were lowered and the exotherm of the reaction was increased, thereby the reaction was promoted. Four reaction pathways were obtained, the order of reaction difficulty is as follows: armchair@Na > armchair > zigzag@Na > zigzag. Thermodynamic analysis showed that four reactions were unidirectional reactions proceeding spontaneously. Kinetic analysis showed that the involvement of sodium the reaction rate constant was increased. Therefore, an in-depth study of the mechanism of the effect of sodium on the heterogeneous reduction of NO with nitrogen-containing char is important for promoting the clean utilization of coal and developing new carbon-based materials for detecting and removal of NO.

Study of Ag2O/TiO2 nanowires synthesis and characterization for heterogeneous reduction reaction catalysis of 4-nitrophenol

Ag2O/TiO2 nanowires as catalyst for reduction reaction of 4-nitrophenol has been synthesized in this study with molten-salt route and followed by the impregnation method. Analysis by characterization results show that the addition of Ag2O does not change TiO2 crystal structure and morphology, and it was found that the impregnated Ag2O has metal-support interactions with TiO2 nanowires. Size distribution of TiO2 nanowires structure along with the Ag2O is known to be within the range of nanomaterial. TiO2 nanowires has an average width of 339.706 nm, and the impregnated Ag2O has an average diameter size of 19.873 nm respectively. The catalytic test performance shows that Ag2O/TiO2 nanowires has excellent result compared to the control sample morphology of Ag2O/TiO2 anatase. It is closely correlated with the electron transfer capability of TiO2 nanowires structure and this shows that Ag2O/TiO2 nanowires is suitable for catalysis of 4-nitrophenol reduction reaction.

A theoretical exploration of the effect and mechanism of CO on NO2 heterogeneous reduction over carbonaceous surfaces

A thorough understanding of the NO2 heterogeneous reduction reaction over a carbonaceous surfaces can help with the goal of providing useful information to aid in controlling NOx emissions. Multiple adsorption structures and reaction pathways on zigzag surfaces were obtained via density functional theory (DFT) calculation, revealing the effect and mechanism of the CO presence and its adsorption mode. Calculation results showed that the introduction of CO at the stage of CO/CO2 desorption accelerates the dissociation of CO2 from a zigzag surface. According to the theory of frontier molecular orbital, the CO presence promotes the transfer of electrons from the char surface to the CO2 moiety, decreasing the energy barrier of CO2 desorption. On the other hand, kinetic and thermodynamic analysis indicates that the introduction of CO during NO2 reduction facilitates the reduction of NO2 to NO, but has little influence on the reduction rate. In addition, the adsorption mode of CO shows little effect on the weak interaction between NO2 moiety and the char edge, but has a significant effect on the weak interaction between CO moiety and char edge. Thus, as the adsorption mode of CO changes, a significant difference in mechanisms can be observed at the stage of CO2 desorption rather than NO2 reduction. To sum up, these theoretical results reveal in detail the effect and mechanism of CO on NO2 heterogeneous reduction, which further explain previous experimental results.

Simulated annealing fitting: a global optimization method for quantitatively analyzing growth kinetics of colloidal Ag nanoparticles.

The involvement of heterogeneous solid/liquid reactions in growing colloidal nanoparticles makes it challenging to quantitatively understand the fundamental steps that determine nanoparticles' growth kinetics. A global optimization protocol relying on simulated annealing fitting and the LSW growth model is developed to analyze the evolution data of colloidal silver nanoparticles synthesized from a microwave-assisted polyol reduction reaction. Fitting all data points of the entire growth process determines with high fidelity the diffusion coefficient of precursor species and the heterogeneous reduction reaction rate parameters on growing silver nanoparticles, which represent the principal functions to determine the growth kinetics of colloidal nanoparticles. The availability of quantitative results is critical to understanding the fundamentals of heterogeneous solid/liquid reactions, such as identifying reactive species and reaction activation energy barriers.

A DFT Study of N2O Homogeneous and Heterogeneous Reduction Reaction by the Carbon Monoxide

ABSTRACT The mechanism of N2O homogeneous and heterogeneous reactions with CO were investigated using density functional theory (DFT). The M06-2X method with the 6–311 G(d) basis set were adopted for geometry optimization and energy calculations of each configuration (reactants, intermediates, transition states and products). Thermodynamic and kinetic analyzes were also conducted to study the influence of temperature on the reaction process. Calculation results showed that there are two channels for the homogeneous reaction between N2O and CO. In addition, the heterogeneous reduction reaction of N2O and CO has two possible reaction pathways due to the different adsorption configurations of CO on char surface. From thermodynamic analysis, the enthalpy difference (ΔH) and Gibbs free energy difference (ΔG) of the homogeneous and heterogeneous reactions are both negative, which indicates that the reaction of N2O and CO is an exothermic process and can take place spontaneously. For the both homogeneous and heterogeneous reactions between N2O and CO, the equilibrium constant of the N2O and CO reaction is always higher than 105 at 800 ~ 1800 K, suggesting that the reaction can be carried out completely. From the kinetic analysis, activation energy of the heterogeneous reaction (137.26 kJ/mol) is much lower than that of the homogeneous reactions (224.53 kJ/mol and 215.89 kJ/mol), which indicates that the reduction reaction of N2O with CO is more likely to take place on char surface. The calculation results explain the reaction mechanism of N2O and CO, which can provide a theoretical foundation for N2O emission.

Mechanism of the Intensification of a Heterogeneous Reduction Reaction with the Liberation of Gas Bubbles

The degree of intensification is estimated for heterogeneous reduction and dissolution reactions by solving the problem of describing the hydrodynamics, mass transfer, and shielding of a reaction surface upon the formation and action of gas-phase products in the form of bubbles. Some theoretical postulates on the formation of gas bubbles in the course of a heterogeneous solid–liquid–gas reaction are considered. Based on the analogy with boiling and bubbling heat hydraulics, theoretical dependences are derived for the bubble growth rate in the presence of a liquid reagent microsublayer. The analytical dependences derived in this work are in qualitative agreement with the empirical relationships of other authors. Due to the complexity of the problems, no special emphasis is laid on quantitative interpretation, but quantitative coincidence may be attained via the introduction of small corrections. The dynamics of a heterogeneous solid–liquid–gas reaction with mass transfer between a liquid reagent and a solid reducer is studied with consideration for the specific features of the hydrodynamics of gas–liquid media. Some relationships for estimating the reagent concentration and the surface-area fraction shielded by liberated bubbles are derived. Estimates show that the effect of shielding is negligible. This seems to be the reason shielding is not taken into account in the technical calculations of reactions with the liberation of bubbles. Reaction stability is investigated to reveal that gas–liquid structures providing the alternation of shielded and unshielded reaction surface areas are formed under equilibrium, thus creating the gas content gradient, which provokes the motion of liquid-reagent layers with intense stirring. An analysis of criterial equations for mass transfer on a reaction surface gives the dependence, which qualitatively and, partially, quantitatively characterizes mass-transfer processes and coincides with the experimental dependence. The results of this work may be used to form the regimes offering the optimal operation of technological reactors.

Electrodeposition of Single Nanometer-Size Pt Nanoparticles at a Tunneling Ultramicroelectrode and Determination of Fast Heterogeneous Kinetics for Ru(NH3)6(3+) Reduction.

We studied extremely fast kinetics of an outer-sphere heterogeneous electron transfer (ET) reaction at a single Pt nanoparticle (NP) using the newly adapted Kotecký-Levich (K-L) method. In this work, an electrode was prepared by nucleating and growing a single Pt NP on a tunneling ultramicroelectrode (TUME) that produces 1-40 nm or greater dimensions. Such a small-size electrode greatly enhances the mass transfer rate, thus enabling us to reliably determine ET kinetic parameters for fast ET reactions. Based on the recently demonstrated K-L model for a general UME, ET kinetic information could be measured by constructing a plot of 1/current density vs 1/mass transfer rate from the series of steady-state voltammograms obtained using Pt NP-deposited TUMEs. For this K-L plot, we altered the mass transfer rates by varying the electrode size, i.e., the Pt NP size in this work. The determined standard rate constant, k(0), of heterogeneous reduction reaction for Ru(NH3)6(3+) was unprecedentedly high, at 36 ± 4 cm/s, confirmed by theoretical simulation. Extended applications to various electrocatalytic reactions with different types of electrodeposited metal NPs will show the versatility of our approach. Particularly, this novel fabrication of a nanometer-sized electrode and its application to fast ET kinetic study with simple instrumentation should be useful in studies of particle size and structure effects on given catalytic reactions.

Continuous regime of chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU) reactivity of CuO oxygen carriers

Chemical-looping with CuO and CH4 presents an interesting reaction system, in which CuO participates in heterogeneous reduction reactions with the gaseous fuel, as well as oxygen uncoupling and catalytic reactions. Therefore, there exists a temperature dependent competition between the processes typically termed as chemical-looping combustion (CLC) and chemical-looping with oxygen uncoupling (CLOU). The objective of this work is to carry out an assessment of the rates of all the relevant reactions involved at various temperatures and thus to show a continuous regime, where the CLC reactions domination proceeds to CuO oxygen uncoupling dominance, as temperature increases. The possible reactions occurring in CuO-based chemical-looping include heterogeneous reactions with Cu oxides, CuO oxygen uncoupling and Cu-catalyzed reactions. The significance of each individual reaction and the corresponding kinetic parameters are experimentally examined in a bench-scale fixed-bed, alternating-flow chemical-looping reactor at conditions relevant to both CLC and CLOU. In situ XRD characterization is used to determine the phases in which Cu exists during reduction and oxidation and possible interactions with the SiO2 oxygen carrier support. A kinetic scheme is proposed, applicable to the entire regime of CLC and CLOU, which is validated with in-house experiments and experimental data from the literature, at conditions where heterogeneous reduction, oxygen uncoupling, Cu-catalyzed, and gas phase oxidation reactions present significant contributions.

New Insights into the Heterogeneous Reduction Reaction between NO and Char-Bound Nitrogen

New insights into the heterogeneous reduction reaction between NO and char-bound nitrogen [char(N)] were obtained by a combination of density functional theory (DFT) and conventional transition state theory (TST). A detailed description of the nature of NO chemisorption is reported based on the HOMO and LUMO, Mulliken atomic charges, and spin densities. It is suggested that, during chemisorption, char(N) contributes electrons to NO. The seven most stable structures (I–VII) resulting from NO chemisorption were identified, and the exothermicity was found to increase in the order III < V < IV < VI < VII< II < I. This finding is reasonable considering the fact that the HOMO of char(N) is predominantly reflected in the active C(2) atom and the LUMO of NO is mainly concentrated on the N(8) atom. Three stepwise reactions leading to N2 formation have been characterized with low energetic penalty acceptable for occurring at the practical heterogeneous combustion temperature. The highest energy penalty was calculat...

Siderophore-promoted dissolution of cobalt from hydroxide minerals

Recent research has revealed that siderophores, a class of biogenic ligands with high affinities for Fe(III), can also strongly complex Co(III), an element essential to the normal metabolic function of microbes and animals. This study was conducted to quantify the rates and identify the products and mechanisms of the siderophore-promoted dissolution of Co from synthetic Co-bearing minerals. The dissolution reactions of heterogenite (CoOOH) and four Co-substituted goethites (Co-FeOOH) containing different Co concentrations were investigated in the presence of a trihydroxamate siderophore, desferrioxamine B (DFOB), using batch and flow-through experiments. Results showed that DFOB-promoted dissolution of Co from Co-bearing minerals may occur via pH-dependent ligand-promoted or reductive dissolution mechanisms. For heterogenite, ligand-promoted dissolution was the dominant pathway at neutral to alkaline pH, while production of dissolved Co(II) for pH <6. It was not possible from our data to decouple the separate contributions of homogenous and heterogeneous reduction reactions to the aqueous Co(II) pool. Cobalt substitution in Co-substituted goethite, possibly caused by distortion of goethite structure and increased lattice strain, resulted in enhanced total dissolution rates of both Co and Fe. The DFOB-promoted dissolution rates of Co-bearing minerals, coupled with the high affinity of Co(III) for DFOB, suggest that siderophores may be effective for increasing Co solubility, and thus possibly Co bioavailability. The results also suggest that siderophores may contribute to the mobilization of radioactive 60Co from Co-bearing mineral phases through mineral weathering and dissolution processes.

Heterogeneous reduction of nitric oxide on synthetic coal chars

Model compounds, with a controlled heteroatoms content and well-defined functionalities, were used to study the release of nitrogen compounds from char combustion. In the present work, the mechanisms involved in NO-char heterogeneous reduction were studied with a synthetic coal (SC) char as carbon source. Another synthetic char (SN) without any nitrogen in its composition was also employed in these studies. Temperature programmed reduction (TPR) tests with a gas mixture of 400 ppm NO in argon and with isotopically labelled nitric oxide, 15NO (500 ppm 15NO in argon), were carried out. The gases produced were quantitatively determined by means of MS and FTIR analysers. Under the conditions of this work the main products of the NO-C reaction were found to be N 2 and CO 2. The main path of reaction involves the formation of surface nitrogen compounds that afterwards react with nitrogen from the reactive gas to form N 2. It was observed that fuel-N also participates in the overall heterogeneous reduction reaction, although to a lesser extent.

Nitric oxide reduction in coal combustion: role of char surface complexes in heterogeneous reactions.

Nitrogen oxides are one of the major environmental problems arising from fossil fuel combustion. Coal char is relatively rich in nitrogen, and so this is an important source of nitrogen oxides during coal combustion. However, due to its carbonaceous nature, char can also reduce NO through heterogeneous reduction. The objectives of this work were on one hand to compare NO emissions from coal combustion in two different types of equipment and on the other hand to study the influence of char surface chemistry on NO reduction. A series of combustion tests were carried out in two different scale devices: a thermogravimetric analyzer coupled to a mass spectrometer and an FTIR (TG-MS-FTIR) and a fluidized bed reactor with an on line battery of analyzers. The TG-MS-FTIR system was also used to perform a specific study on NO heterogeneous reduction reactions using chars with different surface chemistry. According to the results obtained, it can be said that the TG-MS-FTIR system provides valuable information about NO heterogeneous reduction and it can give good trends of the behavior in other combustion equipments (i.e., fluidized bed combustors). It has been also pointed out that NO-char interaction depends to a large extent on temperature. In the low-temperature range (<800 degrees C), NO heterogeneous reduction seems to be controlled by the evolution of surface complexes. In the high-temperature range (>800 degrees C), a different mechanism is involved in NO heterogeneous reduction, the nature of the carbon matrix being a key factor.

Hydrated layered manganese dioxide: Part II. Electrochemical behaviour of some hydrated layered manganese dioxides in alkaline electrolytes

The electrochemical behaviour of some hydrated layered manganese dioxides previously prepared and characterised was investigated by galvanostatic and potentiostatic studies at different conditions of temperature, type of electrolyte and counter electrode, number of cycles and depth of reduction. Reversible range was found to be a homogeneous reaction, which is limited up to 0.23 e −/f.u., whereas the major theoretical capacity is consumed in two heterogeneous reduction reactions yielding Mn(OH) 2 at the end. Spinel-like phases such as hausmannite and hetaerolite are formed during the heterogeneous stage. The formation of the spinel-like phases was found to decrease at low temperature in the absence of aggressive ions such as Zn 2+ and at shallow depth of reduction. The mechanism of the electrochemical reduction of the heterogeneous stage is suggested to proceed via an intermediate with the hydrotalcite structure, which undergoes conversion to Mn 3O 4. The chemical reduction of manganese dioxides was also investigated and was found to support this suggestion.

Mathematical modeling of film chemical reactions of condensed-phase metal oxides with thermal protective materials

The aim of the present work is to mathematically model the film chemical reaction of particles of c-phase oxide metals that have been inertially precipitated from a high-temperature two-phase flow with carbon-graphite TPM. The interaction of high-temperature two-phase flows with carbon-graphite TPM of multilayer walls in the vicinity of the frontal point of spreading of flat or blunt bodies at low collision velocities and substantial mass flows of inertially precipitated polydispersed liquid particles of the c-phase is examined. Under conditions of intense combined heating, a liquid c-phase film appears on the surface of carbon-graphite TPM. It is chemically active and enters into the reduction reaction with carbon, accompanied by the formation of condensed gaseous products. During the direct chemical reaction, the condensed components ensure wettability of the surface, while the gaseous products cool the melt layer by transpiration through it. The liquid c-phase film is an additional thermal resistance to the incident total heat flow, thus ensuring relatively low and moderate contact temperatures, and also has a damping effect through the impact of liquid particles. The liquid film thickness is determined by the competition of mass-transport processes: inertial precipitation of the c-phase particles, spreading and spraying of the melt, its dispersion (mechanical destruction during the transpiration of gaseous products), and suction due to the chemical reduction reaction. A physical diagram of the direct chemical reaction of the melted c-phase metal oxides with carbongraphite TPM of multilayer walls is shown in Fig. 1. We introduce the following main assumptions concerning the mathematical modeling of the interaction of high-temperature two-phase flows with carbon-graphite TPM of multilayer walls by the mechanism of a direct film chemical reaction under conditions of inertial precipitation of polydispersed particles of the c-phase metal oxides in the vicinity of the frontal point of spreading. 1. The hydrodynamics and heat and mass transport in a relatively thin reacting film of the c-phase are described by a model of a laminar incompressible boundary layer of a two-phase, one-temperature, twocomponent "frozen" gas-liquid medium. The inertia and convective terms in the momentum equation are neglected. The dynamic viscosity coefficient of the liquid phase is assumed to be constant. 2. The ablation of the carbon-graphite TPM proceeds by an overall heterogeneous reduction reaction at the contact between the carbon and melted metal oxides, which is described by efficient kinetics and the

Laser raman spectroscopy of lead-zirconate-titanate ceramics during exposure to atomic hydrogen

Raman scattering spectra are measured for lead-zirconate-titanate piezoceramics with measurements performed at varying temperatures and with exposure of the surface to atomic hydrogen. In order to investigate the kinetics of interaction of the ceramic surface with atomic hydrogen, the fixed-frequency time dependences of Raman scattering intensities are obtained as well. These dependences were analyzed and the activation energy of heterogeneous reduction reaction at the surface both for kinetics-controlled and for the diffusion-limited modes of the process were derived. The possibility of studying the kinetics of heterogeneous reduction reactions by an analysis of the time dependence for a fixed-frequency Raman signal intensity is demonstrated.