[Kris001]

Hi, everywone.

I'm looking for exapmles for industrial uses of microvave-assisted production of compounds, using the palladium(II) complexes as catalyst , and i can't find anything. Please for help.

[curiouscat]

I'd love to know too.

There's a bunch of such topics where the article production rate is amazingly high yet industrial use quite hard to find (or at least reflects my ignorance)

e.g. reactive distillation, microwave assisted reactions, sonication assisted reactions

[Corribus]

My guess is - and I could be wrong - that microwave-assisted chemistry on an industrial scale would be cost prohibitive.

[curiouscat]

My guess is - and I could be wrong - that microwave-assisted chemistry on an industrial scale would be cost prohibitive.

Probably right.

It'd help clear the fog if the papers on microwave assisted reactions  were more forthright in acknowledging this.

[Enthalpy]

What kind of microwaves are required? A magnetron for microwave ovens produces 500W at 2.45GHz with 60% efficiency for <20€. Many can be coupled to add power. A special production with other frequency and power would need a limited investment.

[Kris001]

What kind of microwaves are required?

As for any microwave radiation , regardless of the power . I mean generally to the process in the chemical industry involving microwaves and complexes of palladium ( II). Thank you for your interest in the subject .

[Corribus]

What kind of microwaves are required? A magnetron for microwave ovens produces 500W at 2.45GHz with 60% efficiency for <20€. Many can be coupled to add power. A special production with other frequency and power would need a limited investment.

Again, I'm no expert in microwave manufacturing, but the microwave digestion and reaction systems used in the lab are a lot different from those used in your kitchen. The biggest difference seems to be that they are designed to minimize the number of hot spots in the reaction vessel - that is, to limit the variability in the heating rate across the sample. I don't know how easy it would be to scale up that kind of engineering to accomodate a (much) larger reaction vessel. Maybe it's trivial, but I suspect not. Even if it's possible to do, precision on such a scale probably would cost a whole lot of money. My top of the line microwave digester, purchased just this year, costs about 50K, and the maximum mass I can put in a single reaction vessel (not including solvent) is on the order of 1 gram. And that's pushing it. Sample sizes on the order of 250 mg are more practical because of issues with outgassing. Is it possible to scale something like that up to multiples of kilograms? I don't know. Maybe some day, but the fact that you don't hear about it right now is probably giving you the answer.

In most cases, if something is possible to accomplish, but nobody is doing it, then it's usually because it costs too much to do it. Or at least, it costs more than the old way of doing things with little added benefit. In industry, everything is the product of a cost-benefit analysis.

[curiouscat]

My top of the line microwave digester, purchased just this year, costs about 50K, and the maximum mass I can put in a single reaction vessel (not including solvent) is on the order of 1 gram. And that's pushing it. Sample sizes on the order of 250 mg are more practical because of issues with outgassing.

What do you typically use it for? Just curious.

 

In most cases, if something is possible to accomplish, but nobody is doing it, then it's usually because it costs too much to do it. Or at least, it costs more than the old way of doing things with little added benefit.

Wise words. I wish I had a way to send a copy to every overconfident armchair inventor I've met.

[Enthalpy]

At 2.45GHz, heat would appear in the outer centimeters of a watery compound, so big amounts would use a lower frequency, or might flow or move smaller amounts at a constant rate through a smaller heating zone - if the use permits it, or spread the microwave power in the depth through many guides, metallic or dielectric, moving.

When magnetrons served for radars only, they used to cost many k€, because of small production series, but the manufacture is easy - kitchen ovens changed the production volume. I suppose chemical processes are in the first case.

Kris001, apologies for drifting from your query.

[Corribus]

What do you typically use it for? Just curious.

Exclusively for digestion of samples (usually polymers) prior to ICP-MS analysis. Supposedly you can do reactions in it, too, but I've never tried it. It does have an autosampler - each sample takes about 10-12 minutes - but clearly at <1g per sample isn't suitable for industrial scales. I did do some microwave reaction chemistry in grad school, but that instrument could only handle a few mL at a time. Maybe they're much bigger now, I don't know. But I've never seen an instrument capable of doing reactions on the scale of liters or larger. Again, maybe they exist in industry, but I doubt it. The specs for controlling a chemical reaction are so much more stringent than for heating a Lean Cuisine.

Wise words. I wish I had a way to send a copy to every overconfident armchair inventor I've met.

And even if it IS cost neutral, you still have to convince industry to abandon tried and true technologies to take on the new, uncertain methods. There's also ancillary costs in training, method development, and on and on. Tech transfer is just SLOW, even if the economics make sense. Microwave reaction chemistry is still fairly young.

It also depends on the industry. Pharmaceutical industry may be willing to to absorb some cost here and there (or pass it along to customers) for a better process because their margins are so large. Compare that to foods, where profit margins are tiny, and even a few pennies can make the difference between a successful innovation and a stillborn technology. Regulations are also a big part of the equation.

In the end, the science is sadly only a very small part of whether a technology ever actually impacts the world.

[curiouscat]

When magnetrons served for radars only, they used to cost many k€, because of small production series, but the manufacture is easy - kitchen ovens changed the production volume.

It isn't only about economies of scale. e.g. An AN/FPS-2 radar has a 7.5 Megawatt transmitter. How many home microwave oven magnetrons is that?

[curiouscat]

Exclusively for digestion of samples (usually polymers) prior to ICP-MS analysis. Supposedly you can do reactions in it, too, but I've never tried it. It does have an autosampler - each sample takes about 10-12 minutes - but clearly at <1g per sample isn't suitable for industrial scales.

Naive question: So how does it compare to digesting it, say, old-school way using  heat & pressure.  If you used something like an electrically heated autoclave does that work too? Is the microwave hotter? Faster?

Is it sort of the same advantage a home microwave had over gas stoves? Or is there a more novel effect here.

[Enthalpy]

In most cases, if something is possible to accomplish, but nobody is doing it, then it's usually because it costs too much to do it. Or at least, it costs more than the old way of doing things with little added benefit.

Wise words. I wish I had a way to send a copy to every overconfident armchair inventor I've met.

Overconfidence is just a prerequisite of the psychology of any inventor because someone who presupposes he will do worse than what already exists doesn't even give a try. Though, after years of seeing how much the other humans have already invented and how many ideas don't work or aren't adopted, one gets very cautious, yes.

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Heating 100kg of thing by 100K within 1000s takes 10kW permanent RF power (radars emit short pulses), that's only 20 magnetrons for kitchen ovens.

At 13.56MHz, the penetration depth in "water" (depends on ions!) is about 0.2m, and with power coming from all directions, a 0.1m thick item would receive a nicely uniform power. Other materials can be thicker. Kilowatt transistors exist for that frequency.

I'm absolutely confident that uniform power in a big volume is feasible with RF, and not even so difficult - and here I'm in my expertise domain. It may be better to have a set of operating frequencies to adapt to the heated material. What I can't tell is what the chemicals need.

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Being sorry to let Kris001's thread drift, and hoping he'll get the desired answers, I remind he was seeking:
"industrial uses of microvave-assisted production of compounds, using the palladium(II) complexes as catalyst"

[Corribus]

@curious

Three methods commonly used. Microwave-assisted digesion, digestion on a hot plate, ashing. Microwave and hot plate are conceptually similar: add acid and heat the hell out of your sample until it dissolves. Microwave is certainly faster on a per-sample basis, and arguably safer. It's also probably better when high pressures are required. For atmospheric pressures, a simple hot plate approach may be more convenient. But the microwave sounds more sophisticated. In ashing you heat the hell out of your sample, then dissolve the ash in acid, so it's a slightly different process. Serious ICP-MS experts will tell you that there are cases where ashing in a furnace is the preferred method. I am not that level of expert. I use the microwave because that's what was recommended to me. It seems to work ok, but I think ashing may actually be better. I just haven't wanted to invest the time to see. I believe one of the reasons is that you can do far larger samples in an ashing oven because you don't have to worry about outgassing like you do in a pressurized microwave heating chamber. That's the primary reason we are limited to 250 mg per sample with organic polymers. Any more than that and our vessels blow, and/or digestion is incomplete. Of course, if the material won't ash... like a rock... then you have to digest in acid.  Of course, the microwave manufacturers will tell you microwave is superior to all other digestion methods at all times... but the general principle 'each tool for its specific purpose' probably holds. There's no skeleton key for chemical analysis!

(Looks like they have microwave ashing ovens, too. Cool. Didn't know that)

[Kris001]

The best would be if someone had knowledge of industrial processes cross-coupling (Suzuki, Stille, Sonogashira, etc.) Using a microwaves and palladium (II) (This is for my diploma thesis at the Technical University )

EDIT:

Also some information about the prospects for the development of this technology, or microwave reactor with a fixed catalyst bed, as a proposal for a technical solution