Sulfur

00:00:03: Substance.

00:00:04: Stories about the

00:00:05: stuff that shapes our world.

00:00:24: It always needs to be able make sense that you would do something, but in the end is makes a world better than where it's right

00:00:38: now.

00:00:39: Substance I'm Joe Hansen and this is Substance podcast about discoveries and innovations chemistry beyond helping us build sustainable society for future.

00:01:01: In short we tell stories of stuff that shapes

00:01:04: our

00:01:05: world And This episode Our topic is

00:01:08: Sulfur.

00:01:10: Why should you care about sulfur?

00:01:13: You might remember sulfur from chemistry class.

00:01:15: A yellow rock that emits a pretty pungent smell when you burn it, but sulfur is so much more than just the main ingredient in stink bombs.

00:01:25: It's secretly one of the most important substances we use Far More Important Than Most People Think

00:01:34: It's like, it doesn't get more bulk than this.

00:01:40: We make more sulfuric acid then basically any other type of material globally and is used in almost every

00:01:50: fit.".

00:01:50: So Sulfur really key...

00:01:52: This is Marco Kenema the Global Business Director for Oxidation Catalysts at BISF in Shanghai.

00:01:59: While the word sulfur isnot his job description he deals with element a lot Later in this episode, he'll tell us more about how BASF has revolutionized the production of sulfuric acids.

00:02:14: But my first guest is Andrew Shidlow a chemist slash entertainer who will take us on a wild ride through the sulfur

00:02:22: world.

00:02:22: My name Is Andrew Shiddler.

00:02:24: I have a PhD and a history and philosophy of science that my job as a chemistry teacher.

00:02:29: i've been teaching chemistry now for fifty three years.

00:02:32: Andrew's passion For Chemistry started at A very young age.

00:02:36: Well, I suppose it was...I was probably about eight years old.

00:02:39: My parents gave me a chemistry set and i just found mixing the ingredients together was fascinating.

00:02:46: and I think at the age of nine or ten, i was able to make my first ever spontaneous ignition using a glycerin and potassium permanganate.

00:02:56: And that really was beginning for me.

00:02:59: great interest in chemistry... My own ability to achieve something which saw the market as spontaneous combustion.

00:03:07: I can't remember exactly where it would have been probably in the kitchen.

00:03:11: That also didn't go down very well because they filled a kitchen with smoke, and my mother said never ever again will you do experiments at home!

00:03:18: So i started doing them outside in The Open

00:03:21: Air.".

00:03:22: Andrew's love for making fire is what got him into chemistry in the first place... ...and that's why sulfur is just an element to him.

00:03:30: The lump of sulfur is a piece of yellow, it's a yellow solid.

00:03:34: It's like a yellow Lego brick you know?

00:03:36: Sorta that sort-of color and its quite brittle And has no smell or effect on your hand at all.

00:03:44: But solid sulfur is an innocuous substance.

00:03:48: Its quite innocuous until set fire to it Then burns with the blue flame A quiet blue flame emitting the most obnoxious fumes.

00:03:58: You can imagine

00:03:59: A yellow stone that can

00:04:01: burn.

00:04:03: Wow, it's kind of no wonder.

00:04:04: people saw sulfur as something with the potential to transform the

00:04:08: world!

00:04:09: And about thirteen hundred years ago?

00:04:11: The first breakthrough happened.

00:04:14: Beginning in China People started combining sulfur with potassium nitrate and charcoal To make

00:04:19: gunpowder.

00:04:20: And sulfur played a key role because It is much more easy to ignite And it burns rapidly.

00:04:28: No one really knows the exact way in which gunpowder burns, no-one is able to write a chemical equation for the combustion of Gunpowder.

00:04:38: You can write speculative equations but depends on huge number circumstances.

00:04:44: The fact remains unaltered that discovery of gunpowders and role of gun powder in human history is undisputed.

00:04:54: That gunpowder smell, the same one you get from burning matches?

00:04:58: That's the sulfur.

00:04:59: Sulfur dioxide to be precise!

00:05:02: It doesn't smell great for some people but it is nothing compared to hydrogen sulfide a molecule made up of hydrogen and sulfur atoms.

00:05:11: And it reeks like rotten eggs.

00:05:14: Our noses are remarkably sensitive to this stinky substance And that's because being able to smell minute quantities of it is a matter and

00:05:36: it deadens the nerves as well.

00:05:49: So if you smell an amount of hydrogen sulfide, which is too much for your body to tolerate then go on a stage where you can't smell it any longer.

00:05:58: Hydrogen sulfide is also main component in stink bombs but quantities are so low that nobody ever considered them dangerous just very mischievous like Andrew knows from first-hand experience.

00:06:13: I think i must have dropped a few files of stinkbombs.I suspect in the classroom when the teacher wasn't looking and then,the object on that was to make sure that the class would be evacuated.

00:06:24: it would disrupt their lesson And It Was Very Difficult For The Teacher To Find Out Who Dropped This File Of Ammonium Sulfur.

00:06:30: It Was Called A Stink Bomb Of Course But You Mustn'T Tell Me Well I Was Pytonauty Boy At School So I'd Prefer Not To Dwell On That Topic for Too Long.

00:06:38: Let's not dwell on that because Andrew had an even better anecdote about sulfur to share.

00:06:45: And this one goes back over a thousand years ago, the age of alchemists!

00:06:49: You know…the people who were obsessed with trying to turn lead into gold?

00:06:54: In the eighth century, alchemist developed the Sulfur Mercury theory of metals.

00:06:59: In short they believed that all metals including gold are made up different ratios of yellow solid sulfur and liquid silver mercury.

00:07:10: This sounds silly to our modern-day ears, but it was a perfectly plausible theory at the

00:07:16: time.

00:07:16: People in those days in let's say thousand twelve hundred years ago They used thinking differently of world of correspondences.

00:07:24: if something looks like something then that means It might be that thing.

00:07:30: and because mercury is a silver liquid, dense liquid.

00:07:35: Sulfur yellow solid, they reason that it's possible.

00:07:39: in the bowels of earth, sulfur and mercury combined some ways to somehow make all other metals in various

00:07:52: proportions.".

00:07:53: The sulfur-mercury theory lasted for about a thousand years – all the way till the seventeenth century!

00:07:59: Today we know that it is totally wrong.

00:08:02: But since then, We've found many other uses for sulfur.

00:08:07: Sulfur is the fifth most common element on earth.

00:08:11: With a few chemical reactions you can turn elemental sulfur into sulfuric acid Which one of the most important chemicals That we have.

00:08:21: You'd be very hard pressed to spend A single day without using a product that contains sulfuric Acid Even though you might not realize It.

00:08:30: For instance, have you driven in a car today?

00:08:33: Well it wouldn't been possible without sulfuric acid for two very distinct reasons.

00:08:38: Let's start with the first one.

00:08:40: Very few people to they know what a car battery looks like.

00:08:43: that I do because i've been interested and actually repair my own cars And I actually teach automobile engineering Today.

00:08:51: batteries which we had in cars The technical term is called LEN Acid Accumulator acid accumulator is one of the greatest discoveries in the middle-nineteenth century.

00:09:04: The lead-acid battery, which contains obviously lead and acid but the acid it contains is sulfuric acid a thirty percent solution that is quite corrosive with high concentration of Sulfuric Acid.

00:09:20: That's the acid used for lead acid batteries.

00:09:24: And the battery is not the only car park that relies on sulfuric acid.

00:09:29: There's also, The Tires!

00:09:31: And of course everyone takes tires for granted.

00:09:34: They're made in rubber and when they wear out you throw them away.

00:09:38: But it is a very extraordinary achievement That we have been able to invent

00:09:45: A way

00:09:45: Of using rubber which has flexible material An elastic substance To make its hard wearing And that, of course great discovery was the discovery of vulcanization which involved sulfur.

00:10:00: So while you can't turn sulfur and mercury into gold You absolutely need sulfur for car batteries rubber tires and lots of other products.

00:10:11: Let's hear from Marco Kenema From BASF again

00:10:14: The first one Which is probably the most obvious Is a food you eat.

00:10:19: Sulfuric acid is key in the production of phosphoric acid.

00:10:23: So basically any type of phosphate fertilizer, and you also have sulfates that you also include in fertilizer.

00:10:31: so there's two key components at fertilizer for farmers that require sulfuric acid.

00:10:38: another area that's really important is detergents.

00:10:42: The place where you probably can see it the easiest Is on the back of any kind of shampoo.

00:10:47: you'll see something like an alkyl sulfate or something like that.

00:10:53: And those are really the key things that are cleaning your products, so cleaning your hair, cleaning your hands basically cosmetics is probably where people would come in contact with products from sulfuric acid to closest

00:11:07: besides fertilizer and cleaning products.

00:11:09: Sulfuric acid is also a key component in the mining and processing of metals like copper zinc and nickel.

00:11:17: You need sulfuric acid to produce semiconductor chips and refine crude oil into high-quality gasoline.

00:11:25: This broad range of applications makes it clear why sulfuric is the most produced chemical worldwide, with an annual market size of roughly three hundred million tons!

00:11:37: To turn elemental sulfur in this versatile Sulfuric Acid is a multi step process.

00:11:43: you typically would start with sulfur dioxide, so sulfur with two oxygens.

00:11:52: That's really the easy thing to make—you just burn sulfur and then you make SO-II.

00:11:58: And what we want to do is that in order to make sulfuric acid... ...is add one more oxygen.

00:12:06: So you wanna go from sulfur with three oxygents….

00:12:08: …to sulfur with four oxygends.

00:12:11: Basically for that your gonna need a catalyst.

00:12:15: the amount of energy it would take to go from sulfur with two oxygens, to sulfur with three oxygans is pretty substantial.

00:12:24: And then what's the catalyst?

00:12:26: You reduce that energy and you can do at a reasonable temperature.

00:12:30: once you have the sulfur trioxide It's really easy to turn into sulfuric acid.

00:12:36: essentially just add water To make this reaction run safely.

00:12:40: chemists these days doing in two steps But those details don't really concern us today.

00:12:46: What you need to know is that attaching the third oxygen atom, to the sulfur dioxide That's what takes most energy.

00:12:55: Without a catalyst You would heat up a reactor to several hundred degrees Celsius higher than

00:13:01: we do when

00:13:02: use a catalyst.

00:13:04: So over one hundred years ago chemists got work figuring this out And after some trial and error They invented a catalyst that enabled this important reaction at much lower temperatures.

00:13:17: That catalyst is called vanadium pentoxide.

00:13:20: The chemists, hundred years ago were also extremely smart and they knew how to test these different types of materials And understood the periodic table in a lot of detail.

00:13:33: That's where they really came out with this.

00:13:35: It's not even only a vanadium, it is a vanadium with five oxygens which has very strong oxidizing agent.

00:13:43: so its good at putting oxygen on other things or another

00:13:48: atoms.

00:13:49: and that's when once you have development like sometimes you do hit the point were your are going to re-invent wheel

00:13:59: Here.

00:13:59: in short recap just make sure we're all same page.

00:14:02: Vanadium pentoxide helps add one oxygen to the sulfur dioxide, to produce sulfur trioxide.

00:14:11: But like any catalyst, vanadium pentxide is not actually consumed during this reaction – it stays the same and so can be used multiple times!

00:14:22: Still today, vanadium pentoxide is a catalyst of choice for this reaction that people like Marco Kenema always believed could be improved.

00:14:33: One area that BASF started experimenting with was the shape

00:14:58: of very similar to have a star type catalyst.

00:15:04: So Star Ring, so you have a starshape with hole in the middle.

00:15:09: These Star Ring Catalysts are about four centimeters long and look kind of like churros those Spanish deep fried dough sticks that're so tasty when dip them into hot chocolate.

00:15:20: And thats not only improved catalyst.

00:15:22: they've been developing.

00:15:24: And then really in the last seven, eight years, VASF developed the Quattro catalyst.

00:15:32: The first commercial reference for that was in twenty sixteen

00:15:36: and

00:15:36: we've really commercially launched the product in twenty nineteen.

00:15:41: so...and it's probably been one of biggest developments

00:15:50: over time.

00:15:54: This increases the surface area of the catalyst and further improves that conversion.

00:16:04: So what we're trying to do is, were trying to reduce the temperature of the gas coming into the reactor.

00:16:29: With Quattro we can run the reactor at a lower temperature because we have more surface to ignite the catalysts.

00:16:36: so basically you keep the catalyst running and still get conversion which means that you start the reaction in lower temperature.

00:16:50: Quattro significantly lowers the reaction temperature, which conserves energy.

00:16:56: Another advantage of that increased surface area is it helps to convert every last molecule of sulfur dioxide so nothing is wasted.

00:17:06: and lastly The lifespan of the quattro catalysts Is significantly longer than the star ring ones.

00:17:13: with quattros you have nice smooth edges So even if they're rubbing against each other you're not losing surface area.

00:17:21: You are always going to have a similar amount of surface area in the reactor and also less dust formation, which basically means that customer can run for longer time so they don't need to change catalyst as frequently.

00:17:35: Hold on!

00:17:36: Change a catalyst?

00:17:37: Why would I ever NEED to change it if this isn't actually consumed during reaction?

00:17:43: If this confused you... Don't worry we've got you covered.

00:17:47: But let's first consider what a modern-day sulfuric acid production plant looks like.

00:18:12: in some cases up to a meter thick, and then you have the reaction taking place when the gas is blown through that reactor bed.

00:18:27: And now it's kind of what you can think about it in terms

00:18:30: day-to-day.".

00:18:31: Marco Kenema compares the catalyst beds to an air filter that she can find at your car or air conditioning unit.

00:18:38: When that filters clean It's easy to push gas through the air filter But as the filter gets plugged with dust and dirt, this gets harder.

00:18:47: And the same applies to the catalyst.

00:18:51: at The beginning it takes very little energy To push the sulfur dioxide through the catalyst but As the particles rub against each other they create dusts and that among Other things clogs up the pores.

00:19:05: Now you either need more energy to push your gas Through the catalyst bed or your performance straps so You might want to swap out your catalyst for a fresh new one.

00:19:16: Now, the Quattro Catalyst performed better than all other catalysts before it!

00:19:21: It had larger active surface area and higher strength – longer lifespan…and hence a twenty-to thirty percent performance advantage compared with standard sulfuric acid catalysts.

00:19:34: But was Quattros the limit?

00:19:36: It certainly seemed like at least if you sticked in traditional way of producing catalysts which Marco described to me.

00:19:44: So basically when you make a pasta, You need to push it through some kind of dye To get the shape of the pasta.

00:19:52: so When you make A catalyst that's Basically your doing The same thing?

00:19:57: It is like making Pasta but you have Very different material

00:20:01: But its not set in stone That Catalysts Have to be produced this way.

00:20:06: Why Not use a three D printer?

00:20:10: This is how the X-three D catalysts were born.

00:20:14: So if you think about when you three d print at home using your normal Three d printer basically what?

00:20:22: You do?

00:20:22: is you melt plastic and then you do The same thing, you extrude it in a specific position And you have this melted plastic coming through a nozzle.

00:20:34: That's the same concept that we do.

00:20:36: It's just where he was using different materials.

00:20:39: So it's your standard three printing, just very different materials are used.

00:20:44: The new three-D printed catalyst was called X Three Day.

00:20:48: Now each

00:20:48: catalyst unit is a bit bigger than a quarter coin and they look somewhat like breakfast cereal.

00:20:56: Marco Kenema And his team did their best to figure out the optimal shape of the catalyst.

00:21:01: but this Is no easy feat because catalytic chemistry is immensely complicated.

00:21:07: the case for the sulfuric acid catalyst, The actual catalyst activity.

00:21:12: it's a liquid.

00:21:14: It is supported liquid so under reaction conditions active phase actually melt.

00:21:20: So I analyze crystal under room temperature condition but when the catalyst doing what it does its melt.

00:21:30: Its super complex process and you are trying to use your knowledge of chemistry, to understand what's going on under reaction conditions and also very complex analytical chemistry.

00:21:43: To try and figure

00:21:44: out

00:21:45: if you can test under-reaction

00:21:47: conditions.".

00:21:48: Because it is so difficult to figure out If a newly shaped catalyst will be better or worse Marco didn't see much point in wasting hours and hours Of ever more sophisticated tests.

00:22:00: Instead, he just wanted to see how this catalyst performed in real life.

00:22:05: And we said, We'll put it in the reactor and will see what the performance is.

00:22:33: The worst thing that could have happened was that It had the same performance as Quattro.

00:22:38: In the end ,we saw a much better performance than an idea where we were in the right direction.

00:22:44: I think also the fun part Is until we actually started up the plant i didn't really know What's going to happen?

00:22:56: saying that it was going to do what is supposed to.

00:22:59: But until you actually see the data in a plant, and if your catalyst is active at really low temperature below three hundred fifty degrees Celsius... You don't know!

00:23:10: The X-three D Catalyst delivered.

00:23:12: It outperformed the Quattro in many metrics.

00:23:16: That innovative shape led to higher reactor throughput Substantially lower energy consumption And longer lifespan of the catalyst itself.

00:23:25: And when we think about it from a catalyst manufacturing point of view, this is actually the worst case scenario for me because I make money.

00:23:34: When the customer changes their catalyst.

00:23:37: but this catalyst might be so good that the customer doesn't need to change it.

00:23:41: So It's not really in my interest To have this work From company point-of-view But in the end from performance point of you and challenging status quo.

00:23:52: This Is Really The Next Level And it really brings a significant advantage to our customers.

00:23:59: I think that's also the topic where, at the beginning there were lots of people who didn't think this would ever work and my response was always if it makes money for my customer then its only matter time because in end everyone is trying make materials with better price improve their profit get into position can be competition.

00:24:23: And this is one of those step changes where the people who adopted at the beginning really will have a significant advantage over people who come later on in the

00:24:35: game.".

00:24:35: Because the chemical composition of X-three D catalysts are identical to star ring or quattro catalyst, people that want switch catalysts have an easy time doing so!

00:24:46: They simply swap out the old catalyst and fill in x three d.

00:24:51: This was really also one of the key reasons why we went for the technology that we have, because to enter this product into market is going to be significantly lower than if I would come up with a completely new material.

00:25:07: It's still always at risk for our customer and they think it will mitigate that by... Knowing what we can do and making sure that our technical offers give them some peace of mind, but in the end this is a solution.

00:25:24: That works it's tested It's been proven.

00:25:27: In the past BASF wasn't able to produce large quantities of X-Tredi catalysts But now they can.

00:25:33: then Marco Kenema expects that soon sulfuric acid producers will be willing And ready to try these new catalyst out on an industrial scale.

00:25:42: Honestly, if you would have talked to most researchers in BASF in twenty fifteen and asked them If we'd had a commercial production line for three eighty printing sulfuric acid catalysts In twenty twenty six.

00:25:56: I think they all laughed at me.

00:25:59: So...I always say that great innovations come from crazy ideas And i think You need people who are willing To take the risk with a bit of financial eye to see that it actually makes sense for the customer.

00:26:14: And I think that's really key.

00:26:16: when you go into an industrial situation as a researcher, You need be thinking about something which is going help your customers and i think if thats something which was key at BASF we focus on alot because were always trying make innovation that will helps our customer more money.

00:26:34: If u can do that there no limit what the customer will try.

00:26:39: Because if it gives them an opportunity that they can be more successful, That's really a target we all

00:26:45: have.".

00:26:49: in collaboration with Wake

00:27:09: Word

00:27:09: and me, Joe Hansen.

00:27:12: Research and scripting by Daniel Sedbrook Claudia Doyle Hardy Röder And Joe Hanson.