Catalysis and Reaction Engineering Commons^™

Recent Progress In The Mechanistic Understanding Of Formic Acid Oxidation On Pt Electrode, Jie Xu, Dao-Chuan Jiang, Dong Mei, Zheng-Da He, Yan-Xia Chen

Journal of Electrochemistry

This article reviews the recent progress in understanding of the mechanisms for formic acid oxidation on Pt electrode. There are two pathways for formic acid oxidation on Pt electrode: (1) Indirect Pathway through which HCOOH is oxidized to CO₂ through CO_ad intermediate. This pathway contributes only 1% of the total current; (2) Direct Pathway where HCOOH is oxidized directly to CO₂. The results from IR Spectroscopy, single-crystal electrochemistry and DFT calculation all support that the bridge-bonded formate is neither the intermediate of direct pathway nor the precursor for CO_ad formation in indirect pathway. Possible mechanism …

Electrocatalytic Oxidation Of Formate On Pd-Cu/C - Effect Of Dealloying Pretreatment, Kun Jiang, Ye Wang, Tao Lin, Wen-Bin Cai

Journal of Electrochemistry

Carbon supported highly dispersed Pd-Cu nanoalloy catalyst toward formate electrooxidation is prepared via one-pot synthesis by using ethylene glycol as the reducing agent and sodium citrate as the stabilizer. The as-prepared catalyst is structurally characterized by TEM and XRD. The Cu dealloyment is carried out through repetitive potential cycling of the Pd-Cu/C catalyst in an acidic solution. The dealloying effect on the performance of the Pd-Cu/C is investigated by using cyclic voltammetry and chronoamperometry, and the surface structural change of Pd-Cu/C is probed by in situ ATR-IR measurement. The results show that the as-prepared Pd-Cu/C processes a better long-term stability …

Electrochemical Fabrication Of Two-Dimensional Flower-Like Pt Nanostructures For Methanol Electrocatalytic Oxidation, Xia Wang, Jun Hu, Yong-Jun Li

Journal of Electrochemistry

Two-dimensional flower-like Pt nanostructures (2D FPNs) were fabricated on glassy carbon substrates by galvanostatical electrochemical technique. The electrolyte was the HAuCl₄ + HClO₄ aqueous solution without addition of any structure-directing organic reagent, which made as-prepared Pt nanostructures cleaner, exhibiting much higher reactivity. Scanning electron microscopic images revealed that 2D FPNs were spherical Pt nano-flowers constructed by the smallest building blocks, nano-leaves. The number density of spherical Pt nano-flowers can be tuned by controlling the electrodeposition time. High resolution transmission electron microscopic images indicated that each nano-leaf was formed by growing along Pt(111) direction. Electrocatalytic activities of as-prepared 2D …

Preparation Of Pt-Tio2/Graphene Composites With High Catalytic Activity Towards Methanol Oxidation And Oxygen Reduction Reaction, Li Qi, Ying Yin, Wen-Guang Tu, Bing-Bing Wu, Zhao-Sheng Wang, Jian-Guo Liu, Jun Gu, Zhi-Gang Zou

Journal of Electrochemistry

A series of graphene-supported TiO₂ nanoparticles (TiO₂/G) with different TiO₂ contents were prepared by a facile hydrothermal method, and then the Pt-TiO₂/G catalysts were successfully prepared by reducing Pt-precursor with microwave technique. Compared with Pt-G catalysts, the catalytic performance toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) of Pt-TiO₂/G catalysts was improved due to the addition of TiO₂. However, the excessive TiO₂ would lead to a poor catalytic performance of Pt-TiO₂/G catalysts because of the low electrical conductivity of TiO₂.

Effecting Of Dissolved Oxygen On Microbial Fuel Cells Based On Pseudomonas Aeruginosa, Chang-Li Cao, Li-Xiang Chen, Ran-Ran Wu, Ken-Lin Chang, Feng Zhao

Journal of Electrochemistry

In this work, the reaction between the electron shuttle secreted by Pseudomonas aeruginosa and anode was studied by measuring cyclic voltammogram and open circuit potential. The effect of dissolved oxygen on the oxidation reaction of anode was explored. It was demonstrated that the reaction was a diffusion-controlled and reversible process. The anode was a little affected when the dissolved oxygen of inocula was low (0 ~ 1.6 mg·L^-1). The polarization curves showed that the current output of microbial fuel cells decreased 7% with the impact of dissolved oxygen.

Influence Of Crystal Structure On The Electrochemical Performance Of A-Site-Deficient Sr 1-Xnb 0.1 Co 0.9 O 3-Δ Perovskite Cathodes, Yinlong Zhu, Ye Lin, Xuan Shen, Jaka Sunarso, Wei Zhou, Shanshan Jiang, Dong Su, Fanglin Chen, Zongping Shao

Faculty Publications

The creation of A-site cation defects within a perovskite oxide can substantially alter the structure and properties of its stoichiometric analogue. In this work, we demonstrate that by vacating 2 and 5% of A-site cations from SrNb_0.1Co_0.9O_3−δ (SNC1.00) perovskites (Sr_1−sNb_0.1Co_0.9O_3−δ, s = 0.02 and 0.05; denoted as SNC0.98 and SNC0.95, respectively), a Jahn–Teller (JT) distortion with varying extents takes place, leading to the formation of a modified crystal lattice within a the perovskite framework. Electrical conductivity, electrochemical performance, chemical compatibility and microstructure of Sr …

Catalysis In Petroleum Coking, Robert Khakimov, Anya Heinimann, Enrico Martinez, Hyun-Tae Hwang

The Summer Undergraduate Research Fellowship (SURF) Symposium

The petroleum industry is challenged with the processing of present heavy crudes caused by high composition of sulfur and metals, which lead to a higher yield of unfavorable bottom product as vacuum residue. Vacuum residue is the least valuable fraction of four, such as saturates, aromatics, resins and asphaltenes. However, it can be upgraded to recover more valuable products such as light hydrocarbons. The Delayed Coking process is going to be used to transform the vacuum residue at different experimental conditions. First of all, the behavior of the vacuum residue needs to be analyzed with no additions in feedstock. Secondly, …

The Catalysis Of Delayed Petroleum Coking, Anya M. Heinimann, Robert Khakimov, Hyun-Tae Hwang, Enrico N. Martinez

The Summer Undergraduate Research Fellowship (SURF) Symposium

Due to the decreasing crude oil quality (heavier crudes and increasing contaminant concentrations) methods for upgrading residues from the refining process, such as coking, are becoming increasingly important. Delayed coking, a method by which residues are thermally cracked (large heavy molecules broken into smaller lighter molecules), produces liquid products and solid coke which can both be sold for further profit. In order to increase the amount of liquid products produced since they are the most value added product of the coking process catalysts (platinum on 0.5% alumina and nickel (skeletal),molybdenum promoted (1 wt%)) were tested to see how they would …

Synthesis And Characterization Of Microporous And Mesoporous Catalysts For Shale Gas Upgrading, Danesh Contractor, Ravi Joshi, Rajamani Gounder

The Summer Undergraduate Research Fellowship (SURF) Symposium

The petroleum industry is gradually shifting from using naphtha to ethane as its feedstock and new ethane steam crackers are being built. Using ethane as a feedstock produces more ethene and less co-products such as propene, aromatics and C4 alkenes. Thus, the shift in feedstock will reduce the availability of these co-products. Developing methods for the interconversion of alkenes, and specifically using ethene as a reactant, can solve this problem.

This project focuses on synthesis and characterization of zeolites with the BEA framework topology, and their nickel exchanged versions as potential ethene dimerization catalysts. In future work, these materials will …

The Role Of Surface Area In Catalytic Gasification Of Biomass, Elizabeth A. Wachs, Nitish Kumar, Indraneel Sircar, Prithviraja Basak, Jay P. Gore Phd

The Summer Undergraduate Research Fellowship (SURF) Symposium

Gasification of biomass has the potential to provide a carbon-negative source of liquid fuels. The current limited use of gasification is due in part to the high temperatures necessary to achieve high conversion levels. These temperatures can be lowered by the use of catalysts, but the mechanisms by which catalysts affect the reaction rate are not fully understood. Here, the structural component of potassium carbonate’s role in the gasification process was examined. Samples of pinewood sawdust were impregnated with potassium carbonate, then pyrolyzed with N2 in a fixed bed reactor at 750°C (heater thermocouple reading). Half of the char was …

Horseradish Peroxidase-Attapulgite Clay Nanocomposites: Fabrication And Application To Sensing The Extracellular H2O2 Released From Cells, Ping Wu, Chen-Xin Cai

Journal of Electrochemistry

The nanostructured attapulgite clay was employed as a support matrix for immobilizing horseradish peroxidase (HRP). FTIR and electrochemical methods demonstrated that HRP had been effectively assembled on attapulgite surface with the formation of HRP-attapulgite nanocomposites. The HRP-attapulgite hybrid was deposited on the glassy carbon (GC) electrode forming the HRP-attapulgite/GC electrode. Cyclic voltammetric results showed a pair of well-defined redox peaks, which were ascribed to direct electron transfer (DET) of HRP, with the formal potential E₀′ = -335 mV (vs. SCE) in the phosphate buffer solution (PBS, pH 7.0). The dependence of E₀′ on solution pH indicated …

The Ionic Diffusion Model For The Solid Oxide Cathode And Its Verification By The Electrolysis Of Ta2O5 In Molten Cacl2, Hua-Lin Chen, Zhi-Yong Wang, Xian-Bo Jin, George Z. Chen

Journal of Electrochemistry

The deoxidation speed of a solid oxide cathode in molten CaCl₂ can be estimated by the PRS steady diffusion model of O^2-, which correlates the deoxidation speed with the precursor porosity, P, the metal-to-oxide molar volume ratio, R, and the cathode volume shrinkage S. The PRS model indicates that the porosity of the oxide cathode has important influence on the deoxidation speed, and provides a very simple equation for the prediction of the optimal cathode porosity. For the electrolysis of Ta₂O₅, the porosity of the cathode is better to be within 50%. …

Effects Of Oxygen Coverage And Hydrated Proton Model On The Dft Calculation Of Oxygen Reduction Pathways On The Pt(111) Surface, Li-Hui Ou, Sheng-Li Chen

Journal of Electrochemistry

DFT calculation is used to study various possible steps in the oxygen reduction reaction (ORR), including the adsorption and dissociation process of O₂ and the serial protonation process of dissociated products to form H₂O on the Pt(111) surface. By using slabs of different sizes, and different numbers of pre-adsorbed oxygen atoms, the coverage effects on the pathways are investigated. The calculated results using different hydrated proton models are also compared. It is shown that the initial step of the ORR is the formation of a protonated end-on chemisorbed state of OOH*, which can transform to an unprotonated …

Reduction Of Ketoximes To Amines By Catalytic Transfer Hydrogenation Using Raney Nickel And 2-Propanol As Hydrogen Donor, Katherynne E. Taylor

Honors Theses

Ketoximes successfully underwent hydrogenolysis and hydrogenation under catalytic transfer conditions with Raney Nickel and 2-propanol as a hydrogen donor. Ketoximes were reduced to primary amines when 2% KOH was included in the reaction. In the absence of KOH N-isopropyl-secondary-amines were obtained in good yields.

The Effect Of Co-Solvent And Ordered Lattice Structure On Catalysis Of Biodiesel Production In Microreactors, Benjamin J. D. Kegley

Honors Theses

In this study, stable single phase feedstocks for biodiesel production were successfully determined. The addition of free fatty acids, which are considered waste, to the soy bean oil and methanol processing feed as a co-solvent, produces a stable single phase. The single phase feedstock significantly increases initial global rates and supplements the oil with further biodiesel production. A stable single phase feedstock and increased reaction rates are desirable due to the use of continuous heterogeneous biodiesel production in microreactors currently being developed by this research group. Further design improvements to the microreactor design have been determined. Such improvements include the …

Phase Transformations In Calcium Substituted Lanthanum Ferrite, Patrick M. Price

Boise State University Theses and Dissertations

Increasing world energy demands are still heavily dependent on fossil fuels. To meet these demands, crude oil is increasingly being extracted from remote locations where natural gas pipelines do not exist. It is not profitable for oil and gas companies to transport natural gas by ship or truck from these remote locations so it is combusted on site in the form of gas flares. Critics oppose this practice due to the environmental impact from pollution and carbon emissions created during the flaring process. Oil and gas companies are eager to find profitable ways to eliminate natural gas lines in order …

Electro-Catalytic Oxidation Of Hydrogen Peroxide On Au/ L-Methionine /Gc Electrode, Jian-Feng Fan, Xue-Mei Luo, Jing Li, Lou-Zhen Fan

Journal of Electrochemistry

The modified electrodes have been fabricated by generation of Au nanoparticle chains, which was produced by reaction between HAuCl4 and sodium citrate without any additional capping agents or surfactants. The self-assembled Au nanoparticles were attached to the surface of glassy carbon electrode (GCE) layer by layer, using L-methionine (L-Met), thiourea (TU), allyl thiourea (ATU) and polyvinylpyrrolidone (PVP) as a crosslinking agent, respectively. The experimental results showed that the electrochemical performance of the different modified electrodes varied in [Fe(CN)₆]^3-/4- solution. The Au/L-Met/GCE exhibited an excellent electrochemical property, which is superior to other modified electrodes. In addition, the catalysis …

Synthesis Of Platinum Nanocrystallites And Possible Electrocatalytic Properties For Methanol, Lei-Lei Lu, Bao-Zhong Du, Sha Sun, Jin-Fen Niu, Jie Zhao

Journal of Electrochemistry

Platinum nanocrystallites were synthesized by the colloidal method using oxamide as the stabilizer. The morphologies and electrocatalytic performances for methanol of platinum nanocrystallites prepared at different pH values and with different reactant ratios of precursor and stabilizer were investigated. It was found that the platinum nanocrystallites synthesized at pH=5 and with the reactant ratio of 1:20 showed the best electrocatalytic activity for methanol. The peak current density reached up to 1709 μA·cm^-2. Furthermore, the electrocatalytic activity of platinum nanocrystallites for methanol reduced significantly although the cyclic voltammograms in the blank solution were not obviously changed after exposing in …

Preparation Of Pt/H-Tio2 Catalyst With Improved Catalytic Performance For Methanol Electrooxidation, Jin Han, Zhi-You Zhou, Qiang Wang, Miao-Qiang Lv, Chi Chen, Shi-Gang Sun

Journal of Electrochemistry

White TiO₂ nanorods were synthesized by hydrothermal method with TiCl₄ as a precursor. As-synthesized TiO₂ nanorods were further subjected to high-temperature (550 ^oC) heat treatment for 2 h under H₂ atmosphere to prepare gray black hydrogen-treated TiO₂ (H-TiO₂) nanorods with oxygen vacancies and Ti³⁺ interstitial atoms. The Pt nanoparticles of 1.9 nm were supported on these two types of TiO₂ nanorods to form Pt/TiO₂ and Pt/H-TiO₂ catalysts. XRD data indicates that the crystal structure of TiO₂ was still reserved as rutile after hydrogen treatment, but the surface …

Electrocatalytic Oxidation Of Glycerol At The Platinum Electrode Modified With An Nd-Fe-Moo42- Cyano-Bridged Mixed Coordination Polymer, Yong-Jun Ma, Yu-Xiu Tian, Jing Liu, Min Zhou, Jing Ding, Zhi-Mei Jin, Xiang-Mei Wang

Journal of Electrochemistry

A platinum electrode decorated with the ordered Nd-Fe-MoO₄^2- cyano-bridged mixed coordination polymer was successfully prepared by electrodeposition in virtue of the lyotropic liquid crystal soft template methods, and electrocatalytic oxidation behavior of glycerol was investigated on the chemically modified electrode by cyclic voltammetry. The influences of experimental factors such as the concentrations of H⁺ and SO₄^2- in electrolytes, glycerol concentration and scan rate on the electrocatalytic activity of glycerol at the modified electrode were also studied. It indicated that the proper amount of SO₄^2- in weakly acidic electrolyte could help to improve the …

Effect Of Temperature On The Self-Humidifying Open-Cathode Proton Exchange Membrane Fuel Cell, Si-Chen Zhao, Ben Wang, Qiu-Hong Jia, Ming Han, Yu-Hong Xie

Journal of Electrochemistry

Based on the experiments about the output characteristics of a home-made temperature-controlled PEMFC system with atmospheric pressure and no external humidifying condition in different loading voltages and operating temperatures, the optimum operating temperature at different loading voltages can be obtained by tracking the output characteristics of PEMFC operating over a range of temperatures. By analyzing the fitted data the kinetic parameters are evaluated and the effect of different operating temperatures on the PEMFC performance is discussed from a view of electrode kinetics.

Development And Utilization Of A Pair Of Sol-Gel Entrapped Lipases For Biodiesel Production From High Free Fatty Acid Oils, Cory M. Schwartz

Department of Chemical and Biomolecular Engineering: Dissertations, Theses, and Student Research

Biodiesel, which consists of fatty acid alkyl esters, is one of the most widely adopted and successful renewable fuels. Traditional physiochemical biodiesel production methods require high cost refined feedstocks, and so alternative methods of catalysis and feedstocks have been explored. This research investigated the use of polysiloxane entrapped lipases to catalyze the production of biodiesel from low cost feedstocks.

In this work, lipase from Burkholderia cepacia (lipase PS) and lipase B from Candida antarctica (CalB) were separately entrapped using sol-gel chemistry. Optimal reaction conditions for the esterification of free fatty acids by immobilized CalB with methanol were determined. Immobilized CalB …

Influence Of Reduction Promoters On Stability Of Cobalt/Γ-Alumina Fischer-Tropsch Synthesis Catalysts, Gary Jacobs, Wenping Ma, Burtron H. Davis

Center for Applied Energy Research Faculty and Staff Publications

This focused review article underscores how metal reduction promoters can impact deactivation phenomena associated with cobalt Fischer-Tropsch synthesis catalysts. Promoters can exacerbate sintering if the additional cobalt metal clusters, formed as a result of the promoting effect, are in close proximity at the nanoscale to other cobalt particles on the surface. Recent efforts have shown that when promoters are used to facilitate the reduction of small crystallites with the aim of increasing surface Co⁰ site densities (e.g., in research catalysts), ultra-small crystallites (e.g., < 2–4.4 nm) formed are more susceptible to oxidation at high conversion relative to larger ones. The choice of promoter is important, as certain metals (e.g., Au) that promote cobalt oxide reduction can separate from cobalt during oxidation-reduction (regeneration) cycles. Finally, some elements have been identified to promote reduction but either poison the surface of Co⁰ (e.g., Cu), or produce excessive light gas selectivity (e.g., Cu and Pd, or Au at …

Phase Transitions Of Perfluorocarbon Nanoemulsion Induced With Ultrasound: A Mathematical Model, William G. Pitt, Ram N. Singh, Krystian X. Perez, Ghaleb A. Husseini, Daniel R. Jack

Faculty Publications

While ultrasound has been used in many medical and industrial applications, only recently has research been done on phase transformations induced by ultrasound. This paper presents a numerical model and the predicted results of the phase transformation of a spherical nanosized droplet of perfluorocarbon in water. Such a model has applications in acoustic droplet vaporization, the generation of gas bubbles for medical imaging, therapeutic delivery and other biomedical applications. The formation of a gas phase and the subsequent bubble dynamics were studied as a function of acoustic parameters, such as frequency and amplitude, and of the physical aspects of the …

Pulse Electrodeposition Of Pd-Ni Alloy Nanoparticles For Electrocatalytic Oxidation Of Formic Acid, Fang-Zu Yang, Jun-Pei Yue, Zhong-Qun Tian, Shao-Min Zhou

Journal of Electrochemistry

The Pd-Ni alloy nanoparticles with nickel atomic contents of 12.0%, 16.4% and 22.6% were successfully electrodeposited from a Pd-Ni alloy electrolyte by square wave pulse plating. The alloy nanoparticles were in the spherical shape with a diameter of 50 ~ 80 nm. As the growth potential of the alloy was negatively shifted, the nickel content of the alloy was increased, and the size of the nanoparticles was almost the same, whereas the number, the degree of crosslinking and the real active area of the nanoparticles were increased. As the nickel content of the alloy nanoparticles increased, the peak current for …

Synthesis And Electrochemical Properties Of Lico1-XMgXMno4 And Lico1-XAlXMno4 (X= 0, 0.02, 0.05, 0.1) As Positive Materials For Lithium-Ion Batteries, Mei-Ling You, Qing-Song Tong, Xiu-Hua Li, Min Lin, Xing-Kang Huang, Yong Yang

Journal of Electrochemistry

The Al-doped and Mg-doped LiCoMnO₄ materials were synthesized through solid-state reaction. The effects of doping amounts of Mg and Al on the initial capacities, discharge plateaus, and cycle performances were investigated. The morphologies and structures of the as-prepared materials were studied by scanning electron microscopy and powder X-ray diffraction. The results indicate that the as-prepared samples were composed of uniform, well-crystallized particles. The pristine LiCoMnO₄ possessed an initial capacity of 87.0 mAh·g^-1, while LiCo_0.98Mg_0.02MnO₄ and LiCo_0.98Al_0.02MnO₄ delivered 91.3 and 93.6 mAh·g^-1, respectively. The proper …

Fabrication And Impedance Performance Of Gradient Lani0.6Fe0.4O3-δ-Gd0.2Ce0.8O2 Composite Cathodes For Intermediate Temperature Solid Oxide Fuel Cell, Yang Li, Bo Huang, Meng Yuan, Zhi-Qiu Zhang, Zong-Yao Liu, Xu-Chen Tang, Xin-Jian Zhu

Journal of Electrochemistry

A LNF-GDC composite cathode with a gradual change in the composition between ScSZ electrolyte and LNF cathode was fabricated to reduce the cathode polarization resistance (R_p). The gradual change in composition between ScSZ electrolyte and LNF cathode shows the decreases in the charge transfer resistance (R_ct) and gas phase diffusion resistance (R_d). The results revealed that the Rp value, measuring 0.452 Ω·cm² at 750 °C, was the lowest for LNF-GDC composite cathodes with three layers and gradient changes in composition between ScSZ and LNF (Cathode C),, whereas the Rp value of 70%LNF-30%GDC composite …

Study On Carbon Supported Pd Catalysts Modified By Phosphomolybdic Acid For H2O2 Electrocatalytic Reduction, Li-Mei Sun, Cheng Zhang, Ying-Rong Bao, Hong-Xia Li

Journal of Electrochemistry

The Pd/C catalyst was prepared with the chemical reduction method, and phosphomolybdic acid (PMA) was modified on the Pd/C catalyst using the dipping method. The compositions and structures of the Pd/C and Pd/C modified by phosphomolybdic acid (PMA-Pd/C) catalysts were characterized with X-ray diffraction and Fourier Transform infrared spectroscopy analyses. The electrocatalytic activity and stability of the catalysts for the reduction of hydrogen peroxide (H₂O₂) were studied using cyclic voltammetry and chronoamperometry. The results showed that the phosphomolybdic acid was tightly fixed on the surface of Pd/C catalyst through the chemical interaction. The eletrocatalytic activity of …

Preparation Of Pd/Tio2/C Catalyst And Its Electrocatalytic Performance In Basic Solution For Ethanol Oxidation, Qiao-Xia Li, Yi-Chao Yang, Ming-Shuang Liu, Hong-Min Mao, Qun-Jie Xu

Journal of Electrochemistry

Nanoparticles TiO₂ were prepared by hydrothermal method using precursor tetrabutyl titanate. The Pd/TiO₂/C catalyst was synthesized by liquid phase reducing method supported on nano TiO₂ and Vulcan carbon XC-72. The Pd/TiO₂/C catalyst was characterized by XRD, TEM, cyclic voltammetry, and chronopotentiometry. XRD confirmed the face-centered cubic structure of Pd particles, and TEM indicated that Pd particles (size 3 ~ 4 nm) dispersed uniformly on TiO₂ and carbon XC-72. The results from cyclic voltammogram and chronopotentiogram showed the higher ethanol oxidation activity and stability of Pd/TiO₂/C catalyst (20% Pd) as compared with …

Electrochemical Oxidation Of Ammonium Nitrite In Absorption Solution Of Flue Gas, Yong-Hong Lu, Xiao-Bo Dong, Li-Sha Wang, Yan Liu, Chen-Jian Zhu, Hai-Bo Xu

Journal of Electrochemistry

In order to make full uses of ammonium nitrite in absorption solution from flue gas simultaneous desulfurization, denitrification and demercurization processes, here the electrochemical oxidation method was used to transform ammonium nitrite into ammonium nitrate. By using polarization curve, cyclic voltammogram and galvanostatic methods, suitable electrode materials were evaluated and chosen. The influence of electrolyte composition was discussed and the appropriate process parameters were obtained. Finally, the effect of electrochemical oxidation was confirmed by chemical analysis method. In 0.05 mol·L^-1 NaNO₂ + 0.05 mol·L^-1 (NH₄)₂SO₄ simulated absorption solution (5 L, pH = …