Heterogeneous Catalysis - Science topic

Yes, researchers in heterogeneous catalysis and photocatalysis might be interested in testing your new Alluaudite molybdate compounds. These materials often exhibit unique electronic, optical, and structural properties that are promising for catalytic applications, including pollutant degradation, hydrogen production, or selective oxidation reactions. Collaboration with academic institutions, material science laboratories, or industries focused on sustainable technologies could be fruitful. Sharing detailed material characterization and potential catalytic pathways can enhance interest. Engaging in forums or publishing preliminary results may also attract researchers.

Gul Bint Ghulam

1. Place the powder in a glass capillary and determine the decomposition temperature by heating slowly.

2. Determine using a device

Edward Chandler What does the XRD pattern of the support carbon black look like? That is, with no metal loading.

Constrained Minima Hopping method may solve your question. For detailed information, you can refer to the following link: https://wiki.fysik.dtu.dk/ase/tutorials/minimahopping/minimahopping.html.

Building on Amit's answer, established commercially available LTS catalysts are typically used in ammonia and older hydrogen plant flowsheets downstream of the steam reforming and HTS converters. The catalysts are based on Cu/ZnO/alumina, operate at approximately 200oC and usually 30 - 40 bara. CO2 selectivity is very high but these catalysts do produce low level by-products, mainly MeOH and lower levels of other oxygenate compounds. From memory (so this should be confirmed as it's a while since I have worked on LTS Catalysts), the level of these by-products is typically 200 - 1000 ppmv (dry gas basis). Most LTS catalysts contain low level additives (usually Cs2O &/or K2O) to inhibit the MeOH and other oxygenate formation to the lower end of this range.

Recently, S-Scheme system is proposed as an attempt to correct the mechanism of the direct Z scheme [21]. In fact, S-scheme system is nothing but Z-scheme system after considering Fermi level alignment (work function), built-in electric field, and band bending. The need of replacing the name of Z-scheme system with S-scheme is not clear to the authors since the charge transfer mechanism is the same.

Powerful dehydration is by means of azeotropic distillation. Place the dehydrated material in a round boiling flask and cover it with an organic solvent and equip it with a downdraft condenser. Bring the liquid to a boil and collect the distillate. The end of drying can be recognized when the condensate ceases to be cloudy and is clean. Due to the catalytic hydrogenation effects of Ru/carbide, fully hydrogenated Cyclohexane and the distillation temperature of 81C should not be affected. Aromatic hydrocarbons Toluene 110C and an isomeric mixture of Xylenes 1,2, 1,3 and 1,4 (para xylene) with a boiling point from 135 to 140C. Xylenes in particular achieve such a dehydrating performance that I managed to split water from the mono-hydrates of inorganic compounds. The advantage is that the removal of water takes place in an environment without the presence of air.

A cyclohexane ring carbon fully occupied by hydrogen should not react. With the more powerful Toluene and Xylene, there is a risk that it breaks the bond H2O to H-O-H and then hydrogenation and simultaneous hydroxylation due to the loss of the double bond cannot be ruled out.

Here are some links that can help you perform calibration and quantification measurements of TPR experiments.

Best regards,

Cris

Yuxi Xu I really appreciate you clearing up the confusion.

I'm not sure the size of your reactor. for the laboratory scale, the xenon lamp and mercury lamp are suitable because of their high light intensity. But in academic research, LED light sources may be a trend. I have compared conventional high-power light sources and LED in photocatalysis in my previous research, hope it works for you.

Use GC with FID detector and Ar s a carrier gas

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

Zakia Akter Sonia, Just divide the gas flow rate by the catalyst volume, here in cc, and multiply by 60 to refer to one hour.

The best value must be determined but you can work with methanol/oil=12 (molar atio).

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

Hi, Tran Khanh,

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

Safia

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

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

XRD should show peaks for crystalline and amorphous phases as well. Loading may be low and not as reported (5%).

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

Thanks al, for the response please help me I need Complication Neonatal framework

Thank you Sina Safavi

Dear Trey Todor Koev thanks for sharing this very interesting technical problem with the RG community. I'm absolutely no specialist in this field, so perhaps my thoughts are a bit naive. I assume that you just have an acid-base reaction in which the 2-methylimidazole formed a tightly bound sulfonate salt with the ion-exchange resin. In this context, please have a look at the following potentially useful article which might help you in your analysis:

Unfortunately this paper is not freely available as public full text on RG. However, all ten authors have RG profiles, so that it should be no problem to request the full text of the paper dierctly from one of the authors via RG.

Good luck with your work!

Based on my experience, when Cu is introduced by the wet impregnation, the solvent elimination using filtration is not sufficient for some supports. However, the rotary evaporator might be used instead. I have also observed the change in color, however, it did not affect the properties of the calcined catalyst.

Thank you Professor Frank T. Edelmann for the great insight. sure, I'll go through the mention linked. well, from your expertise, will you please suggest some potential materials which can show desired chemistry. Thanks

Dear Sina Safavi thank you for initiating this interesting RG discussion. Although we are inorganic chemists, I'm not an expert in this field. However, I agree with Yurii V Geletii in that there is no such thing as a true catalyst. In this context I suggest that you have a look at the following relevant article which has been published Open Access. It is stated there that future catalysts should be "low-cost and earth-abundant":

(see attached pdf file)

Thank you for sharing idea Madhukar Baburao Deshmukh

Dear All,

I would like to thank you again for your contributions in this discussion which helped me to finalize my recent paper about estimation of number of active sites through kinetic analysis. Last week I got a notification from the editor that it was accepted and soon it will be published. I can share it with you personally if you are interested in.

Best regards,

Thank you for your answer,

this depends on which type of ligand used

I meet the same problem. Have you worked it out?

Wagner model is a rheological model developed for the prediction of the visco-elastic properties of polymers

(TON) number of moles of reactant consumed/(mole of catalyst TON/time of reaction.

Turnover frequency (TOF) = Turnover number/ time of reaction. Hence , TOF indicates the activity of a catalytic centre for the reaction

Raju Kumar , what is the initial temperature of the oven ?

Hi

I have this book. If you need send me an email yo Aimanr@yahoo.com

Adiabatic Fixed-Bed Reactors: Practical Guides in Chemical Engineering

Heterogeneous catalysis the phase of catalysts differs from that of the reactants or products. On the other hand homogeneous catalysis the catalyst is soluble forms a homogeneous mixture with the reactants . The common feature in both types of reactions reaction occurs at the surface .The rate depends upon the amount of the reactants and nature of the substrate. Sterically crowded substrates may undergo the reactions less readily in both the cases.

and products and ... the surface.

I agree with ulián E. Sánchez

Deglycosylated enzymes in which the sugar has entirely removed, especially from a glycoprotein, should be a good choice for your immobilization method.

You can remove most of the moisture by freeze drying.

interesting question

Following the answers

Yes Mr.

Actually, when we try for the annealing of potassium niobate, we suffer from those cracks on the tube. The niobium gets reacted with Si and forms Niobium Silicate. Those cracks are at inner surface of the tube. And cracks get propagated and unfortunately that tube get damaged.

Julián E. Sánchez-Velandia The isotherm is a beautiful example of pore blocking and a desorption step referred to as "cavitation". The isotherm has blended hysteresis characteristics of H2(a), H2(b) and H3/H4 !!

The large cavitation step is due to a significant volume of mesopores (given by the step height) which are blocked by micropores. These papers will explain in more detail exactly what is cavitation:

Both types of reactors (Carberry and trickle-bed) allow to react continuously the feedstock and recover the fluid phase at the exit of the system but maintaining the catalyst inside the reactor. Don't need a filtration system outside the reactor. However it'll be advisable an elemental analysis of the líquid phase at the exit of the reactor since in some liquid-phase reactions the catalyst leaches towards the liquid, It depends on the nature of the catalyst and reactant.

The surface area depends on the dimensions thus if the doping material has comparable size or ( radii) you may get similar surface area.

It is depend on how did you calculate the surface area? I suggest you to run the BET to get the accurate value of the surface area.

The metal content in the impregnation method is usually insignificant (2-5%w), also due to the low solubility of the atmospheric gases in the impregnation solvents (H2O, EtOH, ...) it can be say the atmosphere effects on impregnation are negligible.

use of ultrasonic method, surfactant assisted method and calcination condition (temperature and atmosphere) are more important parameters for enhancing of metal dispersion on supports.

Besides the thermal stability, you can calculate the activated energy, the mass ratio between the combustible and incombustible fractions, and integral procedural decomposition temperature (IPDT).

If there is a COOH group on the surface, then you add one equivalent of hydroxide Me (OH) 3. It reacts with the carboxyl group. Then you heat it up to remove water from the acid salt. You get oxide on the surface of GO.

hello,

you can separate the mixture to enhance the phase rule is F= C-P+2 or F=C-P+1 or F= C-P......

Yes, Halima, but the question was how po prepare Ultrastable zeolite Y. For the increase the stability of Y-zeolite to the level "Ultrastable" its structure must be quite strongly dealuminated, by wery low acid concentration it can be prepared only H-form of Y-zeolite with very small dealumination, and, as you mentioned, it is necessary to calcine it very carefully to keep the crystallinity. Ultrastable Y-zeolite must by prepared by hydrothermal treatment at the temperatures above 500 °C - at this condition a hydrolysis of framework aluminumum occurs creating extra-framework Al-species (EFAL), and Al-vacancies in framework are partially replaced by Si-atoms. Then, EFAL species could be partially extracted by mineral acid - its concentration can be even higher, because after hydrothermal dealumination in e.g. deep-bed conditions at 550-750 °C the dealuminated structure of USY is strong enough to be stable against acid treatment. There are also another methods how to dealuminate the structure of Y-zeolite - slow extraction by H4EDTA-acid, but the hydrothermal steaming is the most used method for the prepartation of Ultrastable Y-zeolite. Method you propose is suitable for H-form of Y-zeolite preparation, but without higher stability.

I understand/guess your material is a sort of an ion-exchange resin in its Na⁺ form. You have been rightly suggested to treat that with dilute HCl solution.

Depending upon the quantity, you may take your material in a column of appropriate dimension (diameter and length) and then charge the column with dilute HCl from top. Monitor the p^H of the liquid coming out of the column from its bottom. Completion of exchange should be indicated by acidity of the out-going solution from the bottom of the column.

With best wishes,

Dear Riikka

Please go through Shah et al. 2015 (Mater Sci Engg B). I do hope you can get some help.

yes its seems correct@Peter Alaba

In my experience with zeolites which reveal different Si/Al ratios, the zeolites which contain more Al can store more ammonia since there are more OH-groups available on the surface. Though NH3 is coordinated not so strong on these hydroxyl groups in comparison to the zeolites with higher Si/Al ratios.

If there is a monomial (irreversible reaction) there is no problem to program such an expression in general. If there is a difference between two monomials (reversible reaction), there is also no problem. However, you need either two reaction rate constants or one reaction rate constant and a equilibrium constant (which can be a number, but it can also be a function of temperature and pressure). But it can be the ratio of polynomials (heterogeneous reaction or enzymatic reaction). Then, however, there are too many possibilities to program it in general. So Fortran, for example. You can program any function there. Unfortunately, there is a problem with physicochemical properties. - One can not have everything. Regards,

You can look for solid base catalyzed Knoevenegal condensation type reaction.

Miroslaw,

I think of fouling as a blockages that cause maldistribution. A burn will sometimes remove a blockage (e.g. if it is coke blocking a pore) but sometimes it will not and dumping and reloading catalyst is often necessary, especially if he blockage is caused by scale/metals instead of hydocarbons.

Coking/carbon disposition is the most common way for commercial Hydrotreating, Catalytic Cracking and Hydrocracking catalyst to lose actiity. Historically these catalyst were :regenerated" with a burn but recently the trend has been to dump catalyst and send it to an offsite regeneration facitity for screnning and coke burning. Arsenic and lead are posons that will permanently deactivate most catalyst and cause them to be unregenerable via burn.

I think of an inhibitor as a material that competes with reactant for catalyst sites inhibition is reversable. If the inhibitor is removed from the feed the rate of the desired reaction will increase. An inhibitor may also increase the rate of coking. If the calayst site is coked up it will usually require a burn(with air or O2) to remove the coke. that has closed up catalysyt pores and/or blocked active sites

.

Poisoning and coking are forms of catalyst deactivation that usually require a stoppage either for regeneration or catalyst replacement.You seem to disagree with the comment it can sometimesbe removed during a regeneration (usually a burn with air or O2). I agree it is not really a "poison" if you can remove it with air/ burn.

All catalyst can be "regenerated" if you take extreme enough measures.

For my purposes - in the refining indusrty- catalyst is not regenerable if activity can not be recovered with a simple burn or other relatively minor procedures like a wash with a solvent.

However even then the active metals can be reclamed and used to make new catalyst.

Hello, Please elaborate you need of simulation a bit more. Both MM and QM and Hybrid QM/MM simulations are possible for any kind of catalysis.

Below is a link and reference to a book for catalytic computation:

Book by RSC

Hope this helps,

Regards

Ajay Khanna

You can make measurements of FTIR using adsorption of pyridine.

Parry, E.P.

An infrared study of pyridine adsorbed on acidic solids. Characterization of surface acidity

(1963) Journal of Catalysis, 2 (5), pp. 371-379

Attached articles may be useful.

1. Based on your data, the catalyst seems to be heterogeneous. Increasing the catalyst amount does not increase the concentration of the catalyst in solution. "Hot filtration method shows reaction stopped after removing catalyst by filtration" indicates that the true catalyst is not in solution.

2. You have already conducted the "specific test"

3. I don't know, but why not.

Before irradiation, it is essential for the target pollutants to get adsorbed on the selected photocatalyst by stirring in dark for 30 to 60 minutes. More adsorption on the catalyst reaction site leads to enhanced degradation.

The precipitation method is generally good for producing bulk catalysts with high purity and homogeneity. You will need to separate the catalyst from solution and deal with (depending on scale) large amounts of salt solutions. You have many ways to control the final product (temperature, pH, additives, solvent etc.). Clearly co-precipitation allows you to make, e.g. mixed oxides.

IWI is like WI but involves knowing accurately the volume of solution needed. This will lead to better dispersion of the metal in most cases. There will be no separation, only drying to remove solvent.

Sol-gel will often lead to porous materials with high surface areas. It provides a high degree of control over properties and allows dispersion at the atomic level.

Physical mixing is the simplest method, but as if often the case with the simpler methods, advantages (other than simplicity) are often lacking.

It would be advisable in your case to check some fundamental texts (e.g. Ertl or Krijn de Jong textbooks on catalysis) to understand differences in more detail. Secondly it would be good to think about the properties you need your catalyst to have - stability, high dispersion, simplicity of synthesis for large scale etc.

I hope this answer is useful and if you have any further questions please ask.

The method that you use is somewhat dependent on the scale of the experiment in question. For slightly larger scale reactions a gas burette system can be used to very accurately measure evolved hydrogen and many universities have them even in undergraduate teaching labs so they are usually very easy to scrounge up. Before trying to fashion a system yourself ask around to see if any other lab or teaching lab has a working system as this can save you a lot of time and effort to build and celebrate your own system. That being said, if no one in your department has a system then the paper mentioned in the previous comment seams like a really good resource. Here is a paper describing a nice setup but a simple setup can be borrowed or fashioned as well. http://aip.scitation.org.proxy.bc.edu/doi/abs/10.1063/1.2968715?journalCode=rsi

For very small samples GC-MS can be a good option but these instruments are expensive and not every department has one.

Electrochemical preparation of PbO2 is well-known , you can use it to get a thick plate that can be crushed into the desired particle size

A heterogeneous system can only be described as homogeneous to a pre-specified or required standard error. There will be a minimum mass required to meet that standard error. The standard error can also be determined practically by experiment.

Hello Onyeka,

The attached review article contains the answer of your question.

Assuming that there are no other functionality that will interfere with the reaction, the difficultly is usually in achieving complete reduction for both.

Colloidal Palladium Nanoparticles with In Situ H2: Reducing System for α,β-Unsaturated Carbonyl Compounds

This paper seems to be able to do the reaction as a single step, but is still dependent on other factors.

I think the best bet will be using NaBH4 and varying the solvent and/or additive to achieve your desired conversion.

One can try condensation using Niobic acid (HNbO3), derived from Nb2O5 I hop[e it will behave like P5O5 and enol form of ketone will under go condensation.

Have you ever heard about Nobel laureate George Olah? Google will help you.

Hi

Fist of all, why do you want to do a RSM (response surface design) ? being a central composite design, composite design in general, Box-Behken design?

- with this question I mean what do you want to achieve as a result from your experimental work:

A process/synthesis/unit operation optimization should be conducted by some steps

(1) Identify a procedure / method that operate

(2) Conduct a parameterization of the procedure, that is to identify the experimental variables that are possible to variety and the responses that can be measured (yield, selectivity, ….)

(3) Conduct an introductory screening design. In this you commonly identify the solvent, catalyst etc. that you should use. In your case you should consult. the paper by Rolf Carlson and collaborators: Strategies for solvent selection. Acta Chem Scand 1985 B39, 79-91 (and the book by Carlson see below).

When you have performed a screening design, where you should include as many variables as possible. Type of design for this purpose: I suggest you to use a fractional factorial design. By such a design you can identify which variables that are the more important and identify a preliminary optimum.

(4) The preliminary identified optimum might subsequently operate as the centre of a new design that allow you to create a predictive model that allow you to estimate: (a) coefficients for single variables, (b) coefficients for the square of each of the single variables and (c) the coefficients for two-factor interactions of the single variables. I strongly recommend to you to use a response surface design of the type central composite design. This allow you to estimate a model:

y(x₁, x₂, …, x_k) = b₀ + b₁x₁ + b₂x₂ + … + b_kx_k + b₁₂x₁x₂ + b₁₃x₁x₃ + … + b₁₁x₁² + b₂₂x₂² + … b_kkx_k²

Be aware that sometimes, the star points of the central composite design cannot be created; e.g. reaction time -1 (10 min)  0 (25 min) +1 (40 min) will result in that “-2” become a negative time:  -5 min.  In such cases you can solve this by change either the value of (-1) increase the reaction time, shorten the step, i.e. the (0) will be at a smaller value. You can also change the value of the star point.

Introduction of the categorical variables such as: “type of solvents”, “type of catalyst”, “type of reactor”, “type of base”,  etc. should not, from my point of view” be included in a response surface design. In fact, such variables shall be investigated by means of a screening design, where all such parameters (variables) is investigated/compared and decided before you do the response surface deign (a composite design).

Some “bibles” for statistical experimental design, screening and response surface modelling and more:

Box, G. E. P.; Hunter, J.; Hunter, W. G. Statistics for Experimenters: Design, Innovation, and Discovery, 2nd ed.; 390 Wiley: New York, 2005.

Box, G. E. P.; Draper, N. R. Empirical Model-Building and Response Surfaces; Wiley: New York, 1987.

Montgomery, D. C.; Peck, E. A. Introduction to Linear Regression Analysis; Wiley: New York, 1982.

Draper, N. R.; Smith, H. Applied Regression Analysis, 3rd ed.; Wiley: New York, 1998.

Rolf Carlson Johan Carlson

ISBN: 9780444515278, Elsevier Science, 8th April 2005

Introducing the Thiele moduli primarily simplifies the form of mass and energy balance equations.

There are no general rules for simplifications of balance equations. One need to consider the rate of reaction / reactions, their reversibility or not and the transport resistances. It is best to use the reaction overall rate / rates when passing from the catalyst grain to the reactor level.

Regards,

I recommend to you, after the preparation of the catalyst to submit it to stability tests. In order to transform the unstable species or tear the active species, and after the stability tests you can prove the catalytic properties in the interest reactions.

In addition, you can determinate the catalytic species who survive to the stability tests.

You posted the second very naive question in this very complex area. Based on your background and your questions you need an experienced  supervisor to guide you in your research. Good luck!

Hi,

It depend on MW of your polymer. NVP with low polymer weight can be easily decomposed in a controlled atmosphere furnace under neutral atmosphere of N2 or Ar without any alteration in MoS2.

Try liquid nitrogen trap

Dear Pratheek,

Example –1Turnover Frequency in Fischer–Tropsch Synthesis

CO   +  3H = 2 CH 4 +     H 2 O

The Fischer–Tropsch synthesis was studied using a commercial 0.5 wt % Ru on  -Al 2 O 3 . The catalyst dispersion percentage of atoms exposed, determined fromhydrogen chemisorption, was found to be 49%.At a pressure of 988 kPa and a tem-perature of 475 K, a turnover frequency, , of 0.044 s  l  was reported for methane.What is the rate of formation of methane, , in mol/s  g of catalyst (metal plus sup-port)?

See this file