EFFECTS OF PREPARATION, Ni/Co RATIO, AND

Ni-Co/AlMgOx bimetallic, Ni/AlMgOx and Co/AlMgOx monometallic catalysts were prepared with various Ni/Co ratios by using the precipitation and impregnation methods for dry reforming reaction. The effects of Ni/Co ratio and preparation methods on the catalyst were analyzed by using different characterization techniques such as BET, ICP, EXAFS, and XANES. It was observed that due to the lack of metal-metal interactions between impregnated catalysts the Ni/Co ratio was better controlled as compared to the precipitated catalysts. On the other hand, with the same Ni/Co ratio the impregnated catalyst was reduced more than the precipitated catalyst. The performance of each catalyst for CO2 reforming of CH4 reaction at 710 °C was studied in a quartz tube reactor. Among the prepared catalysts, the precipitated Ni-Co bimetallic catalyst with Ni/Co ratio of 1 showed the best performance. The Co monometallic catalysts did not show desired activity for CO2 reforming of CH4. Therefore, to observe the stability of the selected catalyst with Ni/Co ratio of 1 a life-time test was carried out for 65 days at two different temperatures of 710 °C and 760 °C. The precipitated catalyst with Ni/Co ratio of 1 showed higher activity and better stability at 760 °C as compared to 710 °C. Finally, the prepared catalysts were poisoned by adding 30 ppm of H2S for CO2 reforming of CH4 reaction. The Ni monometallic catalysts, whether prepared by impregnation or precipitation method, showed better resistance to H2S in all cases. Moreover, the Ni monometallic catalysts had higher ability for regeneration as compared to the other prepared catalysts. It was observed that the prepared catalysts with impregnation were more active and had a higher capability for regeneration after H2S poisoning as compared to precipitated catalysts

Development of ni-co bimetallic catalyst for hydrogen generation via supercritical water gasification of lignin and waste biomass

In this study, a series of Ni, Co mono and bimetallic catalyst supported by Mg and Al were prepared and evaluated for hydrogen production from various model /waste biomass samples via SCWG process. The SCWG tests were conducted at 650 °C, 26 MPa and water to biomass ratio of five. It was found that for catalyst preparation, coprecipitation technique is better than impregnation, and the best catalyst in terms of hydrogen yield is CopCat-2Ni4Co4. The hydrogen yield from different biomass with this catalyst was found to be in the order of: Canola meal \u3e Timothy grass \u3e Wheat straw ~ Lignin \u3e Cellulose. Canola meal was identified as a promising feedstock for hydrogen production from SCWG. Also, the effect of catalyst loading on hydrogen yield was investigated.It was confirmed that high catalyst loading up to 50 wt% is desirable for hydrogen production. Please click Additional Files below to see the full abstract

Development of a Small-Scale Test Facility for Effectiveness Evaluation of Fixed-Bed Regenerators

National Science and Engineering Research Council, Tempeff North America Inc., Winnipeg (Project No:533225-18).Peer ReviewedFixed-bed regenerators (FBR) transfer heat (and moisture) between supply and exhaust air streams in heating, ventilating and air conditioning (HVAC) systems to reduce building energy consumption. This paper presents a new small-scale testing facility to evaluate the performance (i.e. sensible effectiveness) of FBRs for HVAC applications. The major contributions of this paper are: development of a new small-scale experimental facility and methodology for testing FBRs, quantification of uncertainties, and verification of small-scale test data over a large range of FBR design conditions. A numerical model and two well-known design correlations are used to verify the results and testing methodology. The advantages of small-scale testing are that it requires low volume of conditioned airflow, has low uncertainty, requires less exchanger material and has a low cost per test. Moreover, the small-scale testing methodology of FBR would benefit heat exchanger manufacturers to perform detailed sensitivity studies and optimize the exchanger performance over a wide range of design and operating parameters prior to the fabrication of full-scale exchangers

Molecular engineering to tune the ligand environment of atomically dispersed nickel for efficient alcohol electrochemical oxidation

Altres ajuts: ICN2 is funded by the CERCA Programme /Generalitat de Catalunya. Part of the present work has been performed in the framework of Universitat Autònoma de Barcelona Materials Science Ph.D. program. J.L. is a Serra Húnter Fellow and is grateful to ICREA Academia program.Atomically dispersed metals maximize the number of catalytic sites and enhance their activity. However, their challenging synthesis and characterization strongly complicates their optimization. Here, the aim is to demonstrate that tuning the electronic environment of atomically dispersed metal catalysts through the modification of their edge coordination is an effective strategy to maximize their performance. This article focuses on optimizing nickel-based electrocatalysts toward alcohol electrooxidation in alkaline solution. A new organic framework with atomically dispersed nickel is first developed. The coordination environment of nickel within this framework is modified through the addition of carbonyl (CO) groups. The authors then demonstrate that such nickel-based organic frameworks, combined with carbon nanotubes, exhibit outstanding catalytic activity and durability toward the oxidation of methanol (CHOH), ethanol (CHCHOH), and benzyl alcohol (CHCHOH); the smaller molecule exhibits higher catalytic performance. These outstanding electrocatalytic activities for alcohol electrooxidation are attributed to the presence of the carbonyl group in the ligand chemical environment, which enhances the adsorption for alcohol, as revealed by density functional theory calculations. The work not only introduces a new atomically dispersed Ni-based catalyst, but also demonstrates a new strategy for designing and engineering high-performance catalysts through the tuning of their chemical environment

Industrial Ni-Based Catalyst Development for Carbon Dioxide Reforming of Methane

This research work was conducted in three main phases. In the first phase, Ni and Co monometallic and Ni-Co bimetallic catalysts were prepared by using both co-precipitation and impregnation methods. Cylindrical and spherical shaped catalysts were made using the Ni-Co bimetallic catalyst with and without the addition of Boehmite as the binding material. The shaped catalysts were comparably as strong as the commercial spherical alumina ones. The catalysts were also stable and active for carbon dioxide reforming of methane (CRM) reaction in the range of 800 to 900 °C. However, the mass transfer could limit the performance of the spherical catalyst for CRM reaction. Study showed that the external mass transfer limitation could be neglected at high superficial velocity. However, the internal mass transfer was still restricting the performance of the spherical catalyst. Temperature gradients within the spherical catalyst radius were negligible. In the second phase, performance of the Ni-Co bimetallic, Ni monometallic, Co monometallic, and Co-Op commercial catalysts in powder form for steam carbon dioxide reforming of methane (SCRM) reaction at 850 °C were evaluated with various biogas feed compositions. Steam content in the feed gas was the key factor affecting the catalytic performance. The Ni-Co bimetallic, Ni monometallic, and Co monometallic catalysts could not handle a biogas feed composition with more than 12, 15, and 6 mol% of steam content, respectively. The Ni-Co bimetallic catalyst was the most stable than the other evaluated catalysts in a certain range of the steam content. The Ni-Co catalyst and biogas feed 5, which contains about 33% of CH4, 21.5 mol% of CO2, 12 mol% of H2O, 3.5 mol% of H2 and 30 mol% of N2, represent the best combination, not only to produce syngas with the desired H2/CO ratio (1.8 to 2) but also to convert more than 70% of CO2 of the biogas feed. In the third phase, to understand the sulfur poisoning mechanism, CRM reaction over Ni and Co catalysts in the presence of SO2 was studied. CH4 and CO2 conversions increased and H2 and CO along with the by-products of H2S, elemental sulfur and water were produced as soon as SO2 was added to the CRM feed. Mg-Al-Ox support plays a key role in the SO2 poisoning period by providing additional active sites for methane dissociation. Ni, Co, and S K-edges XAS (X-ray Absorption Spectroscopy) of the catalysts showed that species such as sulfide (S2-), sulfite (S4+) and sulfate (S6+) could be formed during the SO2 poisoning. Produced H2S during CRM in the presence of SO2, is likely from the reaction between S2- and H+ intermediates on the catalysts’ surface. When CH4 also dissociated on the metallic sites or sulfur-support intermediates, hydrogen-intermediates reacted with sulfide to produce H2S. Also, when CO2 dissociated on the support, the produced O-intermediate could have reacted with SO2 to form sulfite or sulfate. Monometallic and bimetallic sites and catalyst preparation methods have different impacts on the poisoning mechanism. Co-containing catalysts facilitated sulfate formation while Ni-monometallic catalysts facilitated sulfide formation

International Journal of Multidisciplinary and Current Research The Effect of Explicit and Implicit Vocabulary Instruction on the Reading Comprehension of University Students via Online Classroom

Abstract It is true that vocabulary is central to language teaching as well as learning and is of paramount importance t

Economic Sizing of a Hybrid (PV-WT-FC) Renewable Energy System (HRES) for Stand-Alone Usages by an Optimization- Simulation Model : Case study of Iran

Hybrid renewable energy systems, combining various kinds of technologies, have shown relatively high capabilities to solve reliability problems and have reduced cost challenges. The use of hybrid electricity generation/storage technologies as off-grid stand-alone systems is reasonable to overcome related shortcomings. Solar and wind energy are two rapidly emerging renewable ones that have precedence in comparison to the other kinds. In this regard, the present paper studies four specific locations in Iran, which are candidates for research centers. Based on the solar radiation and average wind speed maps, techno-economically optimized systems are designed by simulating behavior of various combinations of renewable energy systems with different sizing, including wind turbine (WT), photovoltaic (PV), Fuel cell (FC), and battery banks. According to the results obtained by a computer program, it is concluded that the hybrid systems including WT and PV with battery backup are less costly compared to the other systems. Moreover, we found that among non-hybrid systems, in most regions of Iran’s territory PVs are more economical than WTs. Despite of its advantages, FC has not been applied in the optimal systems due to its high initial cost and its low replacement life.Science, Faculty ofNon UBCResources, Environment and Sustainability (IRES), Institute forReviewedFacultyOthe

Development of a Small-Scale Test Facility for Effectiveness Evaluation of Fixed-Bed Regenerators

National Science and Engineering Research Council, Tempeff North America Inc., Winnipeg (Project No:533225-18).Peer ReviewedFixed-bed regenerators (FBR) transfer heat (and moisture) between supply and exhaust air streams in heating, ventilating and air conditioning (HVAC) systems to reduce building energy consumption. This paper presents a new small-scale testing facility to evaluate the performance (i.e. sensible effectiveness) of FBRs for HVAC applications. The major contributions of this paper are: development of a new small-scale experimental facility and methodology for testing FBRs, quantification of uncertainties, and verification of small-scale test data over a large range of FBR design conditions. A numerical model and two well-known design correlations are used to verify the results and testing methodology. The advantages of small-scale testing are that it requires low volume of conditioned airflow, has low uncertainty, requires less exchanger material and has a low cost per test. Moreover, the small-scale testing methodology of FBR would benefit heat exchanger manufacturers to perform detailed sensitivity studies and optimize the exchanger performance over a wide range of design and operating parameters prior to the fabrication of full-scale exchangers

Structure–activity relationships over Ru/NiAl2O4 catalysts in anisole demethoxylation: spectroscopic and kinetic studies

Abstract Demethoxylation  was kinetically and spectroscopically studied over three catalysts with different Ru0/Ruδ+ ratios. In-situ spectroscopic tests demonstrated that the synergy between Ru0 and Ruδ+ was crucial, and Ru0 was in charge of H2 activation and adsorption of aromatic ring while Ruδ+ adsorbed with O in methoxyl. A Langmuir–Hinshelwood kinetic model was proposed, and ratio of Ru0/Ruδ+ was the key in deciding the rate-determining step (RDS): i) desorption of toluene was RDS over catalyst with high Ru0 ratio; ii) dissociation of H2 was RDS over Ruδ+ enriched catalyst; iii) demethoxylation was rate-determined by CO water–gas shift (WGS) when Ru0/Ruδ+ approached ~ 1. The best performance was obtained over Ru/NiAl2O4-200, which effectively enabled both C-O bond activation and rapid recovery of adsorption sites for aromatic rings. Finally, in-situ DRIFT studies on methoxy decomposition and CO-WGS unraveled that the electronic composition of Ru was more stable in Ru/NiAl2O4-200 which contributes to its excellence

Vapor Adsorption Transient Test Facility for Dehumidification and Desorption Studies

The steady state performance testing of industrial-scale energy wheels requires large-scale and advanced instrumentation to analyze large volumes of data. In order to address the feasibility of laboratory-scale studies, experimental modelling and data simulation have been successfully performed by means of the transient and cyclic testing of a heat exchanger within an energy wheel setup in a parallel-flow air stream configuration. However, major challenges have been encountered in terms of predicting the effectiveness of a counter-flow energy wheel configuration in different operating conditions via the use of a transient test setup in a parallel-flow configuration. In the present study, we report the modification of a transient test facility intended to facilitate the more accurate simulation of a full-scale energy wheel operation in a small-scale test facility. A new test section was designed to: (1) enable tests in both counter-flow and parallel-flow configurations; (2) afford automated cyclic testing and achieve the reliable simulation of the energy wheels dehumidification/regeneration cycles; and (3) enhance the accuracy and reduce the uncertainty of the relative humidity (RH) measurements through utilization of the bag sampling method. The latter method is shown to yield greater accuracy with regard to the RH in non-isothermal operating conditions, as well as to reduce the data processing required for the estimation of latent effectiveness