Catalyst Characterization - Science topic

In wet impregnation, the catalyst support and the precursor solution have an excess amount of water. I have read about three methods in the literature: 1. Dry at 80°C while stirring until completely dried, then place in a drying oven. 2. Dry at 80°C while stirring until a slurry state is reached, then place in a drying oven. 3. After impregnation and stirring, use a rotary evaporator until the solvent is removed and it is dry. Scrape off the substance adhering to the inside of the flask, then place it in a drying oven. I used the third method, and I am not sure if this approach results in uniform distribution of the metal. Additionally, I am concerned that the third method may cause the precursor salts to adhere to the inner walls without being loaded onto the carrier, and thus might be scraped off together with it. Although I personally believe that the first two methods also result in uneven distribution and also have metal salts that are not loaded onto the carrier.Thanks.

on catalyst characterization of BET and BJH its well known that BET is for surface area and BJH is pore size distribution but in the BJH result also surface area is reported so what is the diffrence of the surface area by BJH and BET and why we always take BET,in addition to that BET is not recommanded for pores other than meso porous? if thats the case does it mean we should take the surface area by BJH?

How does one gauge sincerity to a cause against mere self-righteousness? Why? My answer: One gauges sincerity to a cause against mere self-righteousness by discerning the observed‘s adherence to reciprocity, harm avoidance, the golden rule(treating others as the treater wants to be treated), the silver rule(NOT treating others as the treater does NOT want to be treated), tradition(what led previous generations to survive and to be anti-fragile), risk analysis(everyone analyzes risks because NO human has complete information to act on), symmetry, empathy, common sense(evolutionary set instincts), human dignity and skin in the game(those paying a more immediate price for the consequence have the greater right to opine as goes with reciprocity and harm avoidance). Plus admitting all humans have the impulses to commit unethical acts and anyone claiming otherwise is disingenuous because no act is completely selfless nor completely selfish. Which consistently leads to an open society with negative utilitarianism(reduce suffering as much as possible without violating before mentioned risk analysis, reciprocity and skin in the game due to desired societal anti fragility).

Difference CO PULSE and CO2 PUSLE CHEMISORPTION for a catalyst characterization ? what are the information we will get from this experiments?

Also the diffrence between the NH3 TPD and Co2 TPD?

Hello - I've been with working with XRD and I've heard people say that increased dispersion of a metal on a support can lead to scattering away of the x-rays from the oxide lattice faces, leading to a decreased intensity of the support peaks. However, XRD is a bulk technique, and given the same metal loading, I'd don't actually see why this is true, and don't want to mention that in a paper without a reference.

Does anyone have an explanation and a reference at least for this happening, if not a reference for an explanation?

Thanks

In this paper how do they calculate? https://doi.org/10.1016/j.ijhydene.2015.05.183

I want to know this C section only. I have only done H2/Ar TPR.

With due respect, I want to inquire about that how I can characterize some noble metal bonded in hydroxide form to some support. We can usually see with the XPS as there would be some binding energy difference but it's hard to differentiate between the chloride form of noble metal and hydroxide. We can see some difference at oxygen O1S in the form of metal-O bond (maybe) but the error range there is also very high. So is there any other possible characterization? Thanks!!!

Can the change of oven temperature program and flow rate of the carrier gas lead to a change in the area of peaks and as a result the response factor values?

I have used 10% H2 with 89 % Ar gas. I want to calculate H2 consumptionc (mmol g-1catalyst )

50 cc/min

How significant is the FTIR study of mixed metal oxide photocatalysts like WO₃-TiO₂ nanocomposites?

Actually I have prepared Al-VPO. But I did not get any peak of Al in the XRD pattern of Al-VPO. So it might be well dispersed or amorphous? If so then which is the active sites if I'll use it for any oxidation reaction?

Please suggest a method to determine this practically. Please avoid mentioning the publications having the final results. The guidelines or procedure for measurement is required. Any related discussion or fruitful comments are warmly welcomed.

Microsoft excel sheet required.

As far as I know, the TGA results should show decreases in weight but my spent catalyst (Ni/ZrO2-SiO2) weight increased.

I know weight gain should only happen if the samples react with the atmosphere: oxidize. But then the graph shows a straight line (100%) until 400-500 ˚C and then it started to increase. No decreases at all.

I suspect that the instrument needs proper calibration. But then, only for spent catalyst have this problem. All the fresh catalysts showed a standard result in which the weight decreases. So I don't think it's the instrument's fault.

Can quartz wool or glass wool increases in weight when temperature increases?

I suspect probably a tiny bit of quartz/glass wool was mixed with the catalyst.

The conditions that I used were 30˚C to 800˚C with a heating rate of 10˚C /min and used air as the carrier gas.

I am trying to make hard pellets of a NiO powder for Van Der Pauw conductivity measurements. Although I have a small steel iron pellet press (1.5cm diameter) and I go as high as 15,000.00 PSI, the pellets disintegrate as soon as I apply even a small pressure on them. I can't use a binder because it would change electronic conductivity, and I tried adding drops of ethanol or heating to 75 degrees °C but no luck. Any advice? 

C1s peak at 284.8 corresponding to Adventitious Carbon is a reference for the X-ray photoelectron spectroscopy (XPS. However, when using carbon-based support, say Vulcan carbon (rich in graphitic carbon), r-GO and GO for deposition of active catalyst.

The C1s peak in these cases will be dominated by sp2 carbons, not by Adventitious Carbon.

How to calibrate the XPS data in that case?

How to account for the charging problem?

Thanks in advance

I wonder which one is more important in means of catalyst design: Number of active sites or TOF value. TOF value already considers number of active sites but the challenging part seems to determine the active sites. Computational methods calculate TOF value without considering number of active sites and experimental methods have different approaches to estimate TOF value, in most of the papers I can not even see the estimation of number of active sites but an ambigious TOF value. If we talk about the catalyst activity TOF value is the measure but if we talk about the catalyst design, shouldn't it be the real textural properties and consequently the number of active sites?

Dear Colleagues,

I’m pleased to inform you that open access journal /Catalysts/ (ISSN 2073-4344, Impact Factor: 3.444) is planning to publish a Special Issue on the topic of "Trends in Catalytic Advanced Oxidation Processes". The submission deadline is 31 July 2020.

Detailed information regarding this issue, please follow the link below to the Special Issue website at:

This Special Issue is dedicated to novel achievements in the field of catalytic advanced oxidation processes. The contributions should be related to the listed topics:

· Catalytic processes in water and wastewater treatment

· Developments in Fenton-like AOPs

· Activation of Persulfates for AOPs

· Formation of sulfate radicals

· Catalytic cavitation-based AOPs (hydrodynamic cavitation and acoustic cavitation)

· Sonocatalysts

· Catalytic ozonation

· Photocatalysts—including visible light and UV applications

· Catalytic wet air oxidation (CWAO)

· Catalytic–electrochemical AOPs

· Carbon catalysts for AOPs

· Nanocatalysts

· Risk of by-product formation during water and wastewater treatment

· Developments in process control of catalytic AOPs (analytical methods, chromatographic, and spectroscopic techniques)

· Methods of catalysts characterization

· Post-process assessment of effluents toxicity

· Application of nanobubbles in AOPs

· Economic analysis of catalytic AOPs application and catalysts life cycle assessment (LCO)

· Industrial catalytic wastewater treatment

· Modelling and optimization of catalytic processes

· Green chemistry aspects in catalytic water and wastewater treatment

Detailed information regarding this issue, please follow the link below to the Special Issue website at:

https://www.mdpi.com/journal/catalysts/special_issues/catalytic_aop

Sincerely hope this invitation will receive your favorable consideration.

Best regards,

Guest Editor

Prof. Grzegorz Boczkaj, PhD. Sc. Eng. Assoc. Prof.

Email: grzegorz.boczkaj@pg.edu.pl

Department of Process Engineering and Chemical Technology, Faculty of

Chemistry, Gdansk University of Technology, 80-233 Gdansk, Poland

Caroline Zhan

Assistant Editor

Email: caroline.zhan@mdpi.com

Catalysts (IF 3.444, http://www.mdpi.com/journal/catalysts)

Could the presence of ligand on a catalyst surface reduced the reactivity of its surface? If yes/no, please explain why?

The NH3-TPD of commercial silica (S.A= 223m2/g) has been run on a Micromeritics 2900 AutoChem II Chemisorption Analyser to determine total acidity. However, there was no peak observed post-run.

The experimental conditions are as follows:

The material was initially pre-treated by heating to 400 ºC under a stream of argon (30 mL/min) at a rate of 20 °C/min for 30 min and then cooled down to 90 ºC under the same stream of argon. A 5 % NH3 in helium gas mixture was then passed through the system and allowed to adsorb onto the surface of the catalyst for 30 minutes. Helium gas (30 mL/min) was then passed through, while the temperature was ramped from 100 °C to 700 °C at a rate of 10 °C/min. The amount of ammonia desorbed was monitored using a TCD.

Why are no peaks observed? is there a possibility the surface hydroxyl groups (if any?) are too weak to interact with NH3 ?

Typically xylene isomerization catalysts convert ethylbenzene (EB) to benzene. But for example, IFP's Oparsi plus catalyst convert EB to xylenes isomers.

It is a big help if anybody tells me what promoter can do this reaction.

I know hydrogenation metals like Pd can convert EB to naphthenes and acid sites of zeolite support are suitable for the conversion of naphthenes to xylene. But I think conventional catalysts have noble metals like Pd and they convert EB to benzene.

I have a catalyst with Cu as the active metal supported on zeolitic and non-zeolitic supports (several different samples). Initial XRD studies and literature studies have indicated the co-existence of both Cu+ and Cu2+ species on my catalytic surface. I need the Cu+/Cu2+ ratio inorder understand my catalytic reaction results. I don't have XPS at my lab so I am striking it off from my options. Please do let me know if there are other methodologies.

The binding energies for my copper based catalyst are strangely low. I do not understand why this is the case. I have looked through different manuscripts but have not found values similar to this. Attached are the deconvoluted peaks for Cu and O1s to better explain the results i obtained. Calibration was done using C1s at 284.8eV

I ran a CO-TPR experiment on an gamma-alumina supported iron catalysts. I'm getting two invert peaks, a small peak at the beginning and a large peak at the end of the temperature range. Iron oxide is normally reduced at around 300C, 480C, and 600C, while I'm just getting the second peak around 480C. I used 10%CO/90%Ar blend as the analysis gas. Sample was degassed under flow of He at 500C, then cooled down to ambient prior to the experiment. Does anyone have any idea why the invert peak is showing up? I have attached the TPR graph and also the experiment log.

I am looking to test the methanol oxidation reaction of catalysts I have prepared. I wish to do this using materials I currently have. I have a glassy carbon electrode for the RDE set up, but do not want to ruin it by depositing my catalyst and nafion on it.

I had done zirconia XPS, from that data I want to calculate % Zr & % O.

I have passivated my catalyst to prevent oxidation; now before promotter addition, I would like to know the temperature to re-reduce the catalyst. That can be presicted by TPR. For the latter, the maximum temperature to reach depends on the thermal stability of the catalyst, hence TGA is beleived to satisfy this aim. I would to know more information that can be derived from such results or if once come accross a similar project.

Hey guys, can you help me solve one question about ZSM-5 deactivation?

The HZSM-5 catalyst was used for DME synthesis reaction with Cu/Zn/Al catalyst. After reaction, the used HZSM-5 catalyst was characterized for TGA and NH3-TPD. The TGA showed 2-3% coking on the used HZSM-5, however, NH3-TPD showed its acidity is close to the fresh HZSM-5. I don't understand.

Hi,

I am working on making an air cleaner, now I need to make a "smoke generator" for my demo device, to show its working principles.

it needs to be stable and generate almost uniform and continues smoke.

my question is that What is the simplest and cheapest method to make a stable smoke generator for this purpose?

I have a PM from @Mahsa Akhgar as follows:

Hi dr alan

I am writing my paper and i face many questions. I hope you could help me. I have synthesized sapo34 catalyst with surfactan but my data has not a specific trend that i cnfused. One of my question is that bet surface area is in relationship with crytal size obtained from scherrer eq. or with particle size obtained from fesem analysis?

Excuseme can i have your phone number or email to ask my questions?

Thanks a lot

Individually, one of them is more active than the other.

Hello everybody

I measured BET surface area and Electrochemically active surface area (EASA) of synthesized MnO2 nanomaterial. EASA was obtained by using Cyclic voltammetry at different scan rates (considering slope (Cdl) by plotting current (mA) vs. scan rates (mV/s)). the slope was obtained to be 0.0487 mF. Here, the carbon clothes (1 cm2) was used as a substrate for MnO2 nanomaterial, and considered Cs = 0.02 mF/cm2. EASA calculated from Cdl/Cs. The mass loading of the MnO2 on carbon cloth was about 0.00036 g/cm2.

1- First question is that "considering Cs=0.02 mF/cm2 as specific capacitance of an atomically smooth carbon meterials" is correct?

2- Second question is that : The BET surface area of MnO2 was obtained to be 17.5 m2/g. But EASA was obtained to be 0.0487 mF (slope), 2.435 cm2 (from Cdl/Cs), and 0.68 m2/g. Why there is high difference between obtained BET surface area (17.5 m2/g) and EASA (0.68 m2/g). Is there somethings wrong with the EASA result or it is correct?

I will be thankful if you could help me regarding two above questions.

Thank you

Anyone having experience of NH3-TPD analysis with activated carbon?

I put this question, because some researchers believe with no real grounds that this phenomenon is connected with the nonexistent surface heterogeneity of the thermally-stabilized catalyst of NH3 synthesis.

Our answer to this question is simple and unambiguous. Oxygen contaminates Fe catalyst because its heat of chemisorption at Fe is very high (about 670 kJ/mol O2, D. Brennan et al, Proc. Roy. Soc., A256, 1960, 81-105; see also https://www.researchgate.net/publication/235342853_Molar_heats_of_chemisorption_of_gases_at_metals_Review_of_experimental_results_and_technical_problems), while the heat of N2 chemisorption is about 125 kJ/mol only and because the temperature coefficient of chemisorption of two-atomic gases at metals is rather small (R.J. Madix, J. Benziger, Ann. Rev. Phys. Chem., 29 (1978) 285-306; see also https://www.researchgate.net/publication/235799473_Oscillation_theory_of_heterogeneous_catalysis_and_its_use_for_identification_of_the_reaction_scheme_and_kinetics_Catalytic_liquid-phase_benzene-ring_hydrogenation_as_an_example), while the temperature coefficient of the H2 interaction with Fe(Oads) is rather high.

The Fe-catalyst surface homogeneity is hardly proved (as for other catalysts) (https://www.researchgate.net/publication/235342837_Surface_homogeneity_vs_heterogeneity_problem_for_thermally_stabilized_crystalline_bodies_and_the_nature_of_heterogeneous_catalysis; https://www.researchgate.net/publication/307920182_Energetic_homogeneity_of_thermally_stabilized_metal_and_metal-oxide_surfaces_new_oscillation_theory_of_catalysis_OTCAT_and_unification_of_catalytic_mechanisms).

It is shown that the applicability of logarithmic isotherm to some adsorption and catalytic data is explainable by the “pantophagy” of logarithmic functions over some fields of parametric variations; as for linear segments in the galvanometric charging curves obtained in some electrochemical works, there are no independent proofs that they result just from H2 chemisorption and it is not proved that the processes attributed to these segments are the equilibrium ones (https://www.researchgate.net/publication/235342837_Surface_homogeneity_vs_heterogeneity_problem_for_thermally_stabilized_crystalline_bodies_and_the_nature_of_heterogeneous_catalysis, p. 10;

https://www.researchgate.net/publication/235342760_Review_of_the_Molar_Heats_of_Chemisorption_and_Chemabsorption_by_Crystalline_Oxides_and_the_Surface_Homogeneity_versus_Heterogeneity_Problem , pp. 572 and 573).

Thus, the return to the opinion on a surface heterogeneity of thermally stabilized catalysts in their catalytic activity has no scientific grounds and sends us back to the erroneous views of the half-century' prescription.

Can it be explained by any theory?

I'm looking for thermal conductivity value (W/m.K) of H-ZSM-5 zeolite catalyst.

I want to know how CA is explained or interpreted in terms of stability of a catalyst material. Can it be used for pointing out anti poisoning ability of a nanocatalyst like Pd ( for eg: while testing for EOR or MOR )

Assume we have to deposit gold nanoparticles prepared using thiols as capping ligand and I wish to deposit it onto the SiO2. To use them for catalysis I need to remove the ligand, which will eventually result in agglomeration of gold nanoparticles. What are the strategies to avoid this?

In fuel cell papers, because they wanted to reduce the precursors of metals to deposit them on their intended support they used reducing agents. However, here I want to exactly fabricate PbO2 on the carbon black powders. Do you think that I should add reducing agent or not. I feel that it is better not to add it. However, I'm not sure whether ethylene glycol (my solvent) can change the PbO2 structure (I mean like oxidizing pbo2 to pb3o4 or some thing like that). Would you please give me your recommendations.

I'm planning to establish a setup for probing with acetonitrile (reactor and spectroscopy). Is there any concern about the molecule staying in the system indefinitely, as in the case of pyridine? The whole setup will be done using stainless steel tube.

Imagine that there are multiple parallel and series first-order reactions. Which reaction is used to represent the reaction rate in the Thiele modulus equation for a sphere, sqrt(k*a^2/D) on pg 46 of the link? The slowest reaction?

E.g.

1) A->B

2) B->C

3) A->D

4) D->C

Acid site and metal site can affect together in the reaction condition. So, it can reduce the catalytic activity since the metal nanoparticle sites cannot survive in the presence of acidic situation. 

I have tested a zsm-5 based catalyst in EB dehdrogenation reaction, and then performed FT-IR analysis for spent catalyst. A peak has been appeared which apparently belongs two both the catalyst and also coke (they cover one another).

How should I interpret this phenomenon?

If you have a source for this situation, would you please introduce?

Thank you in advance

After a solid-liquid heterogeneous catalytic reaction, the catalyst is covered with carbonaceous deposits. I want to analyze the spent catalyst by Raman and maybe also by DRIFTS in order to determine the nature of the coke/deposits. Ideally, if the nature of the deposits allows it, I'd also like to run a TGA in order to determine the (average) amount. But before that, I have a separation problem. How can I remove the remainder of the liquid (organic, b.p. ~240°C) while altering the catalyst and the coke as little as possible? I think it's necessary to remove as much of the liquid as possible, as otherwise it is likely to oxidize and form a gum layer on top of the catalyst. I'll greatly appreciate any suggestions.

The durability test was done by using the following condition: 

 air saturated 0.1M HClO4 , 500mV/s , 1-1.5V V RHE.

Catalyst Preparation:

1mL ethanol, 0.01 catalyst, Nafion ionomer(5wt%) 2 μL.

before durability test, I did cv and ORR. After ORR, I did ADT test.

But, during durability test, I didn't found any significant change.

I made also Pt/PCNF, but there is no change as we see in the paper.

Besides, during CV, at lower scan rate such as 20mV/s Pt-H ads/Pt-H-desorp peak were lower than the peak for pt-oxide formation. But at higher scan rate such as 50mV /s , the peak was okay.

Is anyone have that experience? or do you have any suggestion for that?

Thanks in advance

Generally to know the porosity of the material we use BET characterization. Here im working with catalyst and i want to know the estimation of number of active site of the catalyst. Please help to know this issue. 

Please answer the question as your earliest will helps to improve my concepts.

how we can select catalyst, actually i want to replace acetamide by another catalyst in my acid chloride synthesis reaction.

I have prepared a solid base catalyst from a natural product for the preparation of bio-diesel at different temp. The catalyst is consist of lots of metals and their carbonates, oxides, sulphates, etc. I have characterised it very well. All the characters are interesting at different temp. I like to share one out of them-

The particle size (PZ) usually decreases with increase in temp. But in case of my catalyst, the PZ decrease up 590 deg. preparation temp.  and increase up to 900 deg. and then again decrease up to 1050 deg. preparation temp.

Is this for the melting point of different metals? Are they fused and as a result increase in PZ? Please share....

I found in some articles, concerning the hydrogenolysis of aromatic alcohols using Raney catalysts, that the amount of catalyst used for the reaction is quite high. In some examples are reported substrate to catalyst ratio in the order to 2:5 by weight for Raney nickel and 2:4 by weight for Raney cobalt. Is it because the low activity of the catalyst?

Note that, I have calcined my catalyst at 800 ^oC based on TGA result which became stable, with no weight loss after 800 ^oC.

The reaction temperature is 900 ^oC

Hi, I'm doing a little research for my classes about the catalyst for ethanol steam reform for hydrogen production. So far I found these catalysts:

 Cu/Ni/γ-Al2O3

Co/Al2O3

Co/SiO2

Rh/γ-Al2O3

and Cu and Ni in 

ZrO2 ZrO2/Al2O3 and ZrO2/Y2O3

Do you know any other catalyst? Do you suggest an article about it? Thanks =)

Hi Dear 

I have Xrd file of different phases of MnO2 and the figure shows some peaks which some of them are for α- or β- or γ-, and δ. But I can not distinguish them because some peaks are so close together and I dont know the exact place of peaks for mentioned phases. Please Guide me to find them. 

I will be grateful  for your help. 

Hello Dears

Is there relation between performance and properties of zeolites for different catalysis process?

For example for catalytic converter, zeolite should investigate in terms of TPD test.

Are properties of zeolites general or for each process different?

With regards

Dear All

I prepared N doped TiO2 and I found there are two additional peaks showing in XPS analysis at 716 and 836 eV. Please, may you help me to know what are they belonging to?

Thanks in advance

Regards,

Hi,

I am using MoS2 catalyst for hydrogen evolution reaction. Attached is the Nyquist plot of the MoS2 catalyst.

The measurement conditions are:

1)       open circuit potential

2)       frequencies: 100 kHz to 10 Hz

3)       amplitude 10 mV

The obtained Nyquist plots are deviated from semicircles.

What information could I get from the plots? How could I interpret them?

or

How could I improve my measurement?

Many thanks！

I'm trying to simulate a research paper in ASPEN, so i need to multiply the rate equation with a constant which converts the units from  [(molecules) /(site)(second)] to  [(molecules)/(grams of catalyst)(second)].

please suggest a Book where i can understand determining Turn Over Frequency for a catalyst.

The concentrations of Na2CO3 in the materials are in the range of 10-20 wt.%. Using TEM seems to be straightforward but I wonder if it is an appropriate approach since the atomic number of Al (27) and Na (23) is close to one another. The similarity in atomic number supposes to decrease the contrast and makes it difficult to distinguish between Na and Al. I could not use Scherrer equation since all the XRD peaks corresponding to Na2CO3 disappeared in the supported material.

If not, what technique would give me this information? 

Pyridine FTIR used to analyse the Bronsted and Lewis acidic sites over a solid catalyst. Pyridine vapour adsorbed on acidic catalysts while FTIR spectra is recorded to show the location of Bronsted (1550 cm-1) and Lewis (1450 cm-1). Why a spectra at 1490 attribute to both B and L sites. How pyridine behave here on the surface of catalyst?

Right now we are trying to determine acidity of HzSM5 by pyridine adsorption. We have a temperature reaction cell from Harrick. We pelletize our sample in KBr. After under vacuum at 300 C for 2 hours, pellet is cooled to 50 C. This followed by sending pyridin with N2 flow over the pellet for 30 min. Then we check for pyridine adsorption by taking FTIR spectrum. Then we heat to 100 C and keep under high vacuum for 1 hour. Then spectra is taken. Upto now we couldn't see any peek of pyridine adsorbed on zeolite. Any ideas about what to do?

In addition to the pyridine FT-IR method are there any other methods that can be applied to measure the Nature of different acid sites such as the Bronsted and Lewis acid sites of a catalyst?

Is there a difference between crystallite size and particle size? If and which one affects catalysis? does TEM give crystallite size or particle size?

Hello dears

I want to evaluate porosity for filter diesel particulate and monolith and my sample is as honeycomb (usage as substrate for environmental catalyst) but power.

Can anyone help me to find possible procedure?

I have synthesized a catalyst and I am applying it in catalysing biomass pyrolysis reaction to obtain bio-oil. The catalyst shows best performance when it is used at a concentration of 7% giving the maximum amount of bio-oil. We do not see any further increase in the amount of bio-oil even after increasing the catalyst concentration beyond 7%. Why is it so?

catalysis

My research is about one of hydrotreating process, and my focus is how to Hydrodearomatization napthalene on gasoil fraction (naptha).

The catalyst was NiMo with Al2O3 as a promoter. But, I use the phosphorus acid (H3PO4) as addictive (but it was called impregnation). The problem is, I cant find what was the real effect and how the structure NiMo-P.

Please help me to solve this problem and I cant find paper/journal who explain this. 

I hope everyone can help me :(, thank you.

Why when I increase the doping metal the TPD-NH3 show increasing in acidity then show me decrease at high consecration of the metal?

I am using Ce doped with activated carbon when I increas the  consecration of Ce the acidity was increase then Show me decrease is there any explanation for this phenomena 

thanks

we have prepared solid lewis catalyst by the immobilization of various Lewis acids on the solid support. we have carried out the reaction under solvent-free conditions and also reused the catalyst for five consecutive runs. how can we determine the effect of ph on the stability and activity of the catalyst. further we have checked its thermal stability by carrying out the TGA analysis of fresh and reused catalyst. How can we determine the effect of temperature on the stability and activity of the catalyst

I need to compare the performance of Fe-based catalyst with Pt-C as the baseline for ORR. I am using the LSV at 1600 rpm for comparison. The problem is I am not sure how to interpret the data. The onset potential of the Pt-C is 88 mV more positive but the limiting current density is 14% smaller with the same mass loading. I want to know which one represents the number of active sites limiting current density or the onset potential? can I make any comments about the intrinsic catalytic performance based on the LSV performance if the mass loading is the same or both electrodes? I should make this note that the catalyst is just Fe3O4 with carbon black!

hi I like to study the leaching from my catalyst, I like to run ICP but the problem my catalyst is Heterogeneous catalyst and its insoluble. is there any method to prepare the sample

how can know the type of active sites of the catalysts as well as the reduction degree ,,if dont have TPD and TPR?? 

I record ORR by RDE method. My the current density for ORR usually ranges 4-5 mA/cm2 at 1600 rpm in acid or basic electrolyte. However, the current density appears near 6 at mA/cm2 at 1600 rpm in some good papers. I want to try to get tha same current density with those papers. What is wrong with my experiment? Please tell me some comments on it. Which flow rate of oxygen during measurement is suitable?

I am doing temperature programmed experiments on sofc electrodes sending a mixture of H2/Ar .I thought that the change in dilution of hydrogen affects the amount of this gas contained in the control volume which includes the catalyst. Therefore, if i send hydrogen with higher dilution, there will be more H2 in my control volume and the peaks will be difficult to highlight. Anyway, the partial pressure of hydrogen also affects the rate of reaction and i want it to be high in order to have an higher intensity peak. Which is an optimal value of hydrogen dilution for my purpose? Does it depend also from the gas residence time? In literature the most used values are from 5 to 10 % of H2/inert. Is there any explaination?

Glutathione is an amino acid, hence it exits as a zwitterion. My doubt is whether it acts as acid catalyst or basic catalyst. Please eleborate.