Catalyst - Science topic

Also check please the following useful link: https://www.utsc.utoronto.ca/webapps/chemistryonline/production/reflux.php

Dear Joao G.R. Poco, I agree with abovementioned should work best

Abrar Ali Khan

Investigate the decrease in solubility of Polyoxo tungstate with decreasing pH and catalyst quality. Perhaps you will find a better option.

Respected sir

The image 1 shows two different layers of biodiesel and glycerol.

In image 2, washing of biodiesel is shown. Here, successfully the lower denser layer of water comes first followed by biodiesel. No diffficulty

In image 3, I could not identify is the biodiesel formed or is it the soap formation that took place. and there can be seen 3 layers.Please explain.

Thanks

Also check please the following useful link: https://link.springer.com/content/pdf/10.1007%2F978-1-4684-2796-7_17.pdf

thanks alot

Hi Li Li,

You may make an inquiry at Alfa Chemistry, they offer kinds of good-quality catalysts.

Thanks

Yes, you can use. But make sure that after coating with your catalyst, the electrode surface isn't too thick. If so, then gas molecule formed on to the surface may get trapped and therefore, your electrode efficiency may degrade eventually.

Regards.

For heterogeneous catalysts

Dear Van-Sieu Luc, I have performed many McMurry Reactions however we used actvated Zn dust to reduce TiCl₄ to Ti(0). Prior to reaction, we have purified commercial Zn dust as follows: Zn dust was quickly washed with distilled water containing few drops of conc. HCl (0.5-1% HCl can be used/ I think it's in Vogel's Practical Organic Chemistry book) to remove the oxide coatings in any. Then thoroughly washed with distilled water to make acid free and finally with acetone and dried under vaccum. It can be stored. This Zn dust can be used for reduction of TiCl₄ to Ti (0) in anhydrous dimethoxymethane solvent under reflux under inert atmosphere for 4-5 hours. We used 0.025 gm atom of Zinc for reduction of 0.0126 moles of TiCl₄ and this insitu generated Ti(0) was used for McMurry coupling of 0.003 mole of beta chloro-alpha,beta-unsaturated aldehydes. Yields varied in between 50-92 %. You are welcome to go through the paper "STEREOSELECTIVE SYNTHESIS OF 1,6-DICHLORO-1,3,5-HEXATRIENE DERIVATIVES BY MCMURRY COUPLING

OF beta-CHLOROACRYLALDEHYDE DERIVATIVES" Susmita Gupta, Gandhi K. Kar and Jayanta K. Ray, SYNTHETIC COMMUNICATIONS, 30( 13), 2393-2399 (2000).

I wanna know about what ratio and why we should take in CO2 hydrogenation to methanol production

That's a pretty major question whenever it comes to modelling catalysts that should be "real" to whatever extent and there are several approaches to it, especially when you have a large molecule like cellulose involved:

1) Brute force DFT incl. transition states of a system with realistic sizes is probably unrealistic due to the expensiveness of the resulting calculation.

2) Embedding procedures would allow for the calculation time to shrink while keeping the result somewhat relevant, so you would still have a giant system but only the catalytically relevant system would be expensive DFT while the rest would be MM or semiempirical.

[3) Periodic boundary conditions can help, but since you wrote about crystalline cellulose, I assume you are already doing that, right?]

4) You can also calculate it for a model system which is not cellulose, but has enough resemblance in the reaction zone so you get a result which could be considered acceptable.

Hi Syed,

Your system probably contains water, and the solid is the potassium salt of the acid.

If you add an acid to your solution, assuming it is anhydrous, transesterification can occur.

If your system contains nothing more than your ester, MeOH, and water, the water has no noticeable effect. If the ester contains acids, hydrolysis and re-esterification may occur, as you will see later.

But if your system is not anhydrous and you add acid, the transesterification and hydrolysis can be parallel processes. If the protonated form of the acid is soluble in MeOH, then, at best, the acid will be re-esterified by the MeOH, even if there is some (minimal) water. The rate of this cannot be estimated. In this case, the transesterification is virtual because hydrolysis and consecutive esterification occur.

As for the separatory funnel effect, KOH is a very strong base. When the water touches your solution, hydrolysis starts. Usually, the esters can be extracted (removing the residual acid) with saturated NaHCO3. Somebodies can recommend Na2CO3, but in practice (real life), Na2CO3 solution starts to hydrolyze esters, and if you are not working very fast, a significant amount of ester is lost. So, NaHCO3 is a more failsafe solution.

If you want to remove the base under anhydrous conditions, you can use a strong ion-exchanger (H+). BUT! Wash the activated ion-exchanger to neutral with water and then dehydrate it with MeOH. All ion-exchangers contain impurities and disintegration products, so the first thing is their removal. The ion-exchanger organic impurities are UV active. Water content is a little more complicated, though 5-6 washes with MeOH is enough. Fortunately, the strong H+ ion-exchangers are more stable at moderately high temperatures than the anion-exchanger.

Alternatively, you may add CO2 (dry ice powder) to your KOH reaction mixture because K2CO3 and KHCO3 are insoluble in MeOH, and cooling reduces the reaction rates.

In the end, I would prefer NaOMe. It is soluble in MeOH, and if you see precipitation again, your solution will surely contain water.

Good luck!

Based on personal experience to calculate the pore volume experimentally in a powder that is granulated through a binder (for example, active alumina adsorbent), first remove the moisture from the sample in the oven at a temperature of about 150 °C for about two hours. Then pour a certain amount of granules in a round bottom container and after adding every 3 drops of water to the container by sampler or buret, shake the container and continue this until the sample does'nt stick to the container.The amount of water consumed is calculated per gram of granules you consume.

ICP AES gives the concent of Pd in the catalyst, which is a absolute content value. (0.658-0.358)/0.658*100% of Pd was leaching.

Hello dear Hiba Arous,

Internal combustion engines are heat engines whose heat transfer plays a very important role in their performance and efficiency. In an internal combustion engine, the cooling system is responsible for dissipating excess engine heat. The cooling system of an internal combustion engine consists of many components, one of which is the cooling passage of the cylinder block and the cylinder head. Therefore, you can focus on the effects of the new design of the cooling inlet and outlet position on the engine body temperature distribution and pump power.

Although this is not related to my field of expertise, I recommend it based on my experience working with internal combustion engines.

Good luck!

Dear Ashish, Kindly clean the RRDE shaft with cleaner, sometimes it happens when shaft is not clean.

Raihan Arfin came across this link and I felt it might be the perfect one to go ahead with please go thru and have a look it clearly shows about a review of heterogeneous calcium oxide based catalyst from waste for biodiesel synthesis its a good technical paper and I personally liked it

Dear Alireza Hadi,

I don't know which surfactants are used in TWC catalysts, but only these can cause foaming. May be that acetic acid increase the foaming caused by these surfactants, but acetic acid alone cannot cause foaming.

Dear Jousheed

I am a researcher in the field of ZN catalysts

Z-501 catalyst is a build-up and high active catalyst

And I'm looking for a way to make the Z-509 catalyst

If you want we can share our information

For CaO catalyst the best methanol/oil ratio is 12 (molar ratio).

Hope Graphite rod...

I am looking for a postdoc position in the same area. Please, let me take the position post.

Dear Zhaoxi Sun, Many people used the catalysts with specific facets to calculate the electrostatic potential in most of the publications. My question is that if I didn't find the facet via HRTEM, can I use the facet according to XRD data? Reference: "Noble-metal-free Ni2P modified step-scheme SnNb2O6-CdS-diethylenetriamine for photocatalytic hydrogen production under broadband light irradiation"

I understand you want to increase thermal stability. I am an analytical chemist. It's not about my field. However, I can say this. No matter how many stages of degradation occur, each stage gives you a chance to intervene. The solvent affects the stability. The chromophores, double bonds, aromatic groups carried by the dye reduce the wavelength, and substitute groups such as tert-butyl sec-butly, isopropyl and methyl increase the thermal stability. Removing water from the environment can be beneficial when working with anhydrous dyes.

The type-II heterojunction is the conventional mechanism which describes that, upon irradiation electrons of both the semiconductors (in the photocatalyst) get excited to the CB leaving holes in the VB. Then the lifetimes of these photogenerated electrons and holes are extended because of the shifting of electrons in the CB of the semiconductor with a more negative CB band edge to the CB of the semiconductor with less negative CB band edge and similarly holes will shift towards less positive VB. So, this prevents the recombination of electrons and holes.

In the Z-scheme mechanism, there are donor and acceptor terms involved.

Basically, in this mechanism, photogenerated electrons in the CB of the semiconductor with less CB band edge recombine with the holes in the VB of the semiconductor with less positive VB band edge. Thus, unwanted electrons and holes recombine and this enhances the lifetime of strong photogenerated electrons (in the CB of semiconductor with more negative VB band edge) and holes (in the VB of semiconductor with more positive VB band edge) which will subsequently take part in the photocatalysis.

This is the basic difference.

Yu et al. have explained these mechanisms in detail in their paper. (10.1016/j.chempr.2020.06.010)

Without the exact composition of the slurry, the carrier used and the treatment conditions nobody can give You the information You are asking for.

CaO is used for transesterification. TiO2 is a well-known photocatalyst, maybe their combination can be useful.

André Oliveira , you can also check out their materials in this link (https://www.owlnet.rice.edu/~ceng403/hysys/pfex.htm). I believe it would be of help to you. Regards

Dear Radha N Somaiya ,

You could see the next papers:

Best,

Fran

I think if you use H2O2 35 % the water is sufficient to form diol, to increase the formation of diol you can realize the reaction in presence of acid, for example a solid acid like NAFION, more easy to remove after the reaction

I will try it and see the result. Thank you, Mr. Yurii V Geletii

Dear Aroldo José Romero-Anaya many thanks for posting this interesting technical question on RG. I'm not a proven specialist in heterogeneous catalysis, and I'm not going to name yet another commercial supplier. According to the rather instructive Wikipedia entry at https://en.wikipedia.org/wiki/Fischer–Tropsch_process the Fischer-Tropsch reaction is best catalyzed by molybdenum carbide as well as by cobalt-, iron- and ruthenium-based catalysts. My suggestion would be to first decide which metal(s) you want to employ (after reading one or two reslevant review articles) and than search for commercial suppliers of the indvidual catalysts.

Good luck with your work!

Hi, Tran Khanh,

To increase the selectivity of limonene oxidation, is it possible for you to protect, before, the endocyclic double bond?

Safia

Hello Viraj,

thank you for posting this very interesting technical question on RG. We work in the field of synthetic inorganic chemistry, so that I would not call myself a proven expert in the field of heterogeneous catalysis and transesterification. However, I can suggest to you two very instructive review articles which will certainly help you in your analysis. Thus please have a look at the following references:

Fortunately this paper has been posted by the authors as public full text on RG, so that you can freely download it as pdf file.

The other paper can also be accessed as public full text as it has been published Open Access:

(Please see the attached pdf file)

I hope this helps. Good luck with your work!

Hello Pawan,

thank you for sharing this very interesting technical qestion with the RG community. Previous studies in this field have shown that the transition metals Ni, Fe, Rh, and Pd have the best possible catalytic activity in this context. For more detailed information please have a look at the following relevant literature reference:

The full text of the Open Access article is freely available on the internet (please see the attached pdf file).

Good luck with your work!

During the synthesis of g-C3N4, your carbon and nitrogen precursor (urea or melamine) resulted in the condensation, dehydration and polymerization reactions simultaneously. These reactions resulted in huge weight loss in your product. However, the material is lightweight and contains a high specific volume. This could be the main reason for the yield difference in high g-C3N4 catalysts to low g-C3N4 catalysts.

Hello Melford,

thank you for sharing this interesting chemical question with the RG community. There is a vast body of literature regarding the synthesis of sulfonamides available, and there are different synthetic routes and various catalysts known. Thus the choice of the "best" catalyst depends on the indiciofual synthetic route (e.g. starting with sulfonyl chlorides). In other words, there is no general answer to your question. I suggest that you use RG directly as a valuable source of information. For example, search the "Publications" section for terms like "catalyst for sulfonamide synthesis". This will provide you with many relevant literature references which have been posted by RG members, some of them even as public full texts:

Good luck with your work and best wishes!

Dear Sadie Padilla Baez

Can you add the reference you mentioned so we can get into the details and maybe help you a bit more?

Regards,

Check this Web application https://youtu.be/GTJP15sB1Tw

Its fast, accurate and free.

Hi, Noe Arjona Thank you very much for the information. Sure please I will.

After the last reaction analysis is complete. Dilute it with methanol and wash it, centrifuge again, the catalyst will be better recovered.

Dear Ali Behrad Vakylabad thank you for sharing this very interesting chemical question with the RG community. We work in organometallic chemistry, so the I'm not an expert in this field. However, for a first overview I can suggest to you the following relevant literature reference:

Fortunately this article has been posted by the authors as public full text on RG, so that you can freely download it as pdf file. Moreover, you can also contact the corresponding author directly via RG at https://www.researchgate.net/profile/Agnieszka-Jastrzebska-4.

Good luck with your research!

Excuse me,please, but it is more or less basic knowledge.

look for instance

:Heinrich Remy: Lehrbuch der Anorganischen Chemie. Band I und II, Akademische Verlagsgesellschaft Geest & Portig, 12. und 13. Aufl. Leipzig 1973

BUT a small correction of my previous text: PH of the metal solution should be lower then 2.

Dear Viraj Miyuranga . See the following useful link: http://www.bioline.org.br/pdf?st11020

As I understand...you need to do BET analysis. Any group working on polymeric sensors will be capable of such studies. In my knowledge, IIT Delhi and DRDE, Gwalior should be capable of this.

Hi, Magnetic stirrer and RB flask are enough to reach out TiO2-RGO composite (https://www.sciencedirect.com/science/article/abs/pii/S1004954118308759)

If you want methodology in a detail, kindly let me know.

I would like to recommended this article

https://www.sciencedirect.com/science/article/abs/pii/S1385894716307677

Hi,

Very good points Szymon! To me also it seems sometimes impossible to compare the results in electrocatalysis due to different measurement and calculation procedures.

Talking about degradation tests, I am not sure about ORR, but in water splitting electrocatalysis the reason why different procedures are all accepted may be that these tests are usually performed in much harsher conditions that is required for industrial applications and they all pass the criteria defined for them to be called "stable".

I suggest reading this paper which is in water splitting electrocatalysis but can be a help for you too!

"Anantharaj, S., et al. "Precision and correctness in the evaluation of electrocatalytic water splitting: revisiting activity parameters with a critical assessment." Energy & Environmental Science 11.4 (2018): 744-771."

Good luck!

Arash

Dear Lenida Kyndiah thank you for posting this important question on RG. It is certainly of broad interest to many other RG members as well. My suggestion is to use RG directly as a valuable source of information. For example, you can check the "Questions" section of RG to find closely related question. In this context it might be helpful reading the answers given to the following questions which have been asked earlier on RG:

(15 answers)

and

(34 answers)

These are just two typical examples. Good luck with your work!

Dear Tai Yong Lee, these references are just simple examples in support of my previous answer. Worth to mention is that the effect of catalyst concentration is well seen in coordination polymerization such as Ziegler-Natta and in step-growth (polycondensation) polymerizations. Have a nice reading. My Regards

Dear Noor Aljammal many thanks for posting this very interesting technical question on RG. Please note that we are synthetic inorganic chemists (organolanthanide chemistry), so that I am not a proven expert in either organic synthesis ot heterogeneous catalysis. However, to the best of my knowledge, aldol condensation reactions are often heterogeneously catalyzed by different metal oxides such as MgO or ZrO₂. Since you are talking about a spent catalyst, it appears clear that you are using a heterogeneous one. However, unfortunately you did not further specify in more detail the nature of your particular catalyst. As you certainly know, the success of heterogeneous catalysis largely depends on many different factors such as preparation and pre-treatment of the catalyst, particle and pore sizes, surface area, pore size distribution, and of course other reaction conditions such as solvent and temperature. Thus all I can do right now is to suggest to you two potentially useful literature references in which the acitivties of freshly prepared and spend aldol condensation catalysts has been studied in detail. One possible reason for the higher activity of the spent catalyst could be the presence of more OH^– ions on the surface after the first reaction. Thus please havve a look at the two articles in the attachment.

I hope this helps answering your question. Good luck with your work and best wishes, Frank Edelmann

It is necessary to carefully analyze the conditions of synthesis and measurements (!!!) and find out what and when has changed. Only you can do this yourself. Therefore, it is very important to carefully record all conditions of experiments.

Examples. One of my colleagues (it was a long time ago) almost went crazy trying to understand why the effect he discovered periodically disappears. As a result of the brainstorming of his colleagues, it turned out that the effect was detectable only from 9 to 11. Everything turned out to be simple - at this time his experimental table was illuminated by the sun's rays, but not at other times and on cloudy days. A similar situation was with the seasonal switching on of heating (the experimental setup was located too close to the heating radiator). But the funniest case was with TG. The results of experiments on two different setups often did not match. Then it turned out that one of them was located not far from the workplace of a very corpus person, who often passed nearby.

Manish Ramchandani Manish Ramchandani yes, the reaction rate depends on the reactants. However, most of the amides follow this hydrolysis reaction.

For defect-free graphene or nanotubes, you can have a 2D mode without a D-mode because the D-mode is symmetry-forbidden without defects while the 2D-mode is symmetry-allowed both for defected and undefected material.

However, if a G mode is absent, I would be very careful to claim something is a 2D mode.

In the case of your spectra, it is hard to tell what kind of physics is going on for spectra 1-4. That feature is not really a sharp peak as you would expect from a regular Raman process.

I previously taught at 4 different universities while conducting my own clinical research so as to avoid a potential conflict of interest involving these two roles. So I was very careful in this regard.

Now being retired, I am free to be me!!

Rich

Oxygen saturation means the concentration of oxygen in solution at given pressure of O2 in the gas phase. This is called a solubility of oxygen. "how exactly the oxygen concentration can affect the ORR activity?" I would expect an increase of the reaction rate with an increase of oxygen pressure in the gas phase.

The problem with CO2 is its increase in the atmosphere. In that respect, there will be no increase. There are processes as we all know that use renewable energy sources to produce hydrogen. In the meantime, gasoline will be used in diverse applications. So we should congratulate and encourage this type of study.

👍

Thank you Bezzi Hamza

Could anyone give me an example of a real catalyst developed by help of the Sabatier Principle? I cannot, sorry.

This Principle is only one of many aspects You should have in mind developing catalysts.To predict the activity of heterogeneous catalysts for a given reaction, above all You need a lot of experience for the given catalytic system.

Furfural is a neutral compd. However exposure to whether it may get oxidized o furoic acid slowly.Hence it may act as a weak acid.

Here some ideas:

In catalysis when you analyze the rate dependence (rate(x,y,z, ...)) an initial point would be to carry an adequate experimental design of the testing experiments. Surface response methodology (using Box-Behnken, central composite, etc. designs) is/are the most utilized way to do it.

Another point is that normally the treatment of light (intensity, as well as more complex issues related to the rate of photon absooprtion) would need to be considered (mostly to provide results with general validity).

Finally, using (and validating) a reaction mechanism would provide you some ideas about pseudo-order(s) of reactions. This is likely the more complex point and some ideas about mechanisms based on light-included methodology (as well as ideas from spectrocopy to support them) can be found in:

Dear Sheraz Yousaf

Years ago, I have with my colleagues a trial for determination of foam's GSA system and it was complicated. Now, I found the EUROPEAN PATENT [EP 2 764 916 B1] presenting in section [0024] and beyond related sections a simple procedure for GSA determination of Ni foam coating. Hope it helpful.

Best regards

Dear Ximena Ortiz many thanks for sharing this very interesting technical question on RG. I'm actually not a specialist in this field, but I just came across the following potentially useful article which migth help you in your analysis:

Unfortunately this paper has not yet been posted as public full text on RG. However, two of the authors have RG profiles. Thus you can easily contact one of them via RG and request the full text. Normally, authors respond quite rapidly to such full text request. Perhaps they can also help you directly with your question as they are expert in this field of research.

I hope this helpy. Good luck with your research and best wishes, Frank Edelmann

Dear Yogeshsing Rajput ,

Yes, you can use L9 (34). But you should notice that you should use Pulled Error for response of variable parameter.

I draw your attention to following article:

Good luck!

Considering the fluorescence origin, CDs were encapsulated in silica matrices by reacting a silane precursor with surface hydroxy groups that do not contribute to the emission process. It enables CDs in the uniform dispersion in silica to preserve their narrow emission in the solid state by avoiding aggregation.

To enhance the optical properties, stability and to preserve emissions

In terms of the methanol synthesis process and catalyst background, I suggest another two older sources. These are

* The Catalyst Handbook 2nd Edition (1989; edited by M V Twigg and copyright M V Twigg) [ISBN 1 874545 35 9] - see Chapter 9 p441 "Methanol Synthesis";

* "Ammonia. Methanol, Hydrogen, Carbon Monoxide - Modern Production Technologies" by Max Appl - published by Nitrogen journal (copyright 1997 CRU Publishing Ltd) [ISBN 1 873387 26 1] - see Chapter 3 "Methanol".

For recent process and catalyst information, I suggest looking at the web sites, literature, conference/journal papers and patents for the following companies.

* Process licensors: Johnson Matthey; Haldor Topsoe; Air Liquide Lurgi; Methanol Casale.

* Catalyst suppliers: Johnson Matthey; Haldor Topsoe; Clariant.

These comprise the major companies involved in each area but there are others.

Dear Sahar Talebipour you aksed "And I have another question about flexible catalyst, what does it mean? Flexible?" Please find an answer to this question in the following link. It is outlined here that certain innovative ceramics can be designed to being flexible, malleable and thin as paper:

In this context please also have a look at the following relevant research article:

Fortunately this article is freely accessible as public full text on RG.

Good luck with your research and please stay safe and healthy!

What is the flow reactor design? If I assume it is a section of cylindrical tube with some means of catalyst grid or other support, then the size of the pellets relative to the flow reactor diameter should be considered. If there are less than ~10 pellet diameters (for cylindrical pellets calculate the equivalent diameter, d(eq)) across the reactor diameter, then there can be wall effects that impact gas flow through the catalyst bed and so the apparent performance of the catalyst. I suggest finding a text that describes this in more detail as I'm working from memory!

Ahh Bugs replacing refinery process again. A 50+ year old dream that will probably come true some day - but probably not in my lifetime.

Ansari Palliyarayil

In addition to the excellent answers provided by Gerhard Martens and Yuri Mirgorod I would also examine what is measured by XPS and XRD in terns of penetration gap and the type of catalyst (I worked with such catalysts in my Ph.D when dinosaurs ruled the earth with both XRD and XPS - indeed the 7th ESCA/XPS system in the world...). In XPS you're looking at maybe the top surface 10 - 15 atomic layers only which is invariably fully oxidized and thus Pd²⁺ will show strongly from the shift in eV. You'll only start to 'see' the bulk if you (for example) argon ion etch the system. With XRD (dependent on the sample and element) you'll have a great deal more penetration (perhaps, in theory, up to a micron or more). In this latter case you'll see more of the bulk Pd⁰ metal. In XRD you can distinguish the lattice spacing of Pd from PdO (as Gerhard Martens states) and not the oxidation states. One other technique that would be extremely valuable to you is TPR (Temperature Programmed Reduction). If you have the ability to reduce the system (by hydrogen) in your XPS set up then you'll easily be able to remove the oxide and see the Pd metal reflections only.

It can be calculated from UV data of photocatalyst as well as DRS data of photocatalyst. While using UV data Tauce's equation is used. While in other case kubelka munk equation is ised

Dear Loveneesh Kumar thanks for sharing this very interesting technical question with the RG community. According to the relevant literature reference cited below, a "hot filtration test alone cannot prove that the reaction occurs heterogeneously":

Fortunately this article has been posted by the authors as public full text on RG, so that you can freely download it as pdf file.

It might also be worth a try to check the answers given to the following closely related questions which have been asked earlier on RG:

(4 answers)

and

(58 answers)

Good luck with your work and please stay safe and healthy!

Also check..

Dear Narayanan Subramanian thanks for sharing this interesting chemical problem with other RG members. I'm not really familiar with rigid polyol synthesis, but I know that disodium pyrophosphate is only slightly acidic. My suggestion would be to add some phosphoric acid in order to neutralize the remaining 10% of KOH. It might be worth a try. Good luck with your work and best wishes!