After deciding to overcome the barrier of transition metal catalysis first, Xu Yun and others quickly put on a standard experimental suit.
Students who have passed high school chemistry should know this.
According to the periodic law of elements, people often look for catalysts in the region of transition metals.
For example, the catalyst for ammonia synthesis is an iron catalyst.
Vanadium pentoxide is a catalyst for the synthesis of sulfuric acid and nitric acid.
Raney nickel, etc. are often used for the addition of olefins and hydrogen.
Why do these transition elements and compounds often play the role of "moon elders"?
Let me first explain a concept to you in human terms:
Feedback π key.
When a transition metal atom...that is, a coordination bond is formed between the central atom and the ligand.
Coordinating atoms will provide lone pairs of electrons to fill the empty orbitals provided by the central atom.
This forms a σ bond in the form of a coordination bond.
sometimes.
Some electrons from the central atom may also fill in the empty orbitals of the ligand molecules.
This is the feedback π bond.
And in this process.
The antibonding orbitals π2py* and π2pz* of the ligand molecule are empty.
When it acts as a ligand.
It can not only provide lone pairs of electrons to coordinate out, but also provide π anti-bonding empty orbitals to coordinate electrons in.
As long as the central atom and the ligands have lone pairs of electrons and empty orbitals, the prerequisites for coming and going are met.
Coupled with the suitable symmetry of the two, a feedback π bond is formed.
See here.
Smart students should understand.
That’s right!
If a ligand molecule forms a feedback π bond with a certain transition metal atom, its originally empty π antibonding orbital will be filled with electrons.
The bond level is negatively related to the number of electrons in the antibonding orbital.
The more electrons filled in the antibonding orbitals, the smaller the bond level and the weaker the bond.
N≡N, which was originally very strong, has been weakened by the feedback bond, which means that its chemical activity has been greatly enhanced.
In other words.
If you want the ligand molecules to react again, it will be easier to do so.
This is the principle of transition element catalysis.
Very simple and easy to understand.
The transition metal used by Xu Yun and others in the laboratory is ruthenium, a metal with very stable properties and strong corrosion resistance.
There is another very special situation about this thing:
Its content in the earth's crust is only one part per billion, making it one of the rarest metals.
But it is very cheap and is the cheapest metal among the platinum group metals.
But cheap is cheap.
Because its crystal structure is a hexagonal unit cell, it can only be used in the laboratory during the production of imidacloprid and cannot be successfully used in industrial production.
"So among the candidate solutions given, we appended three metals: lanthanum, scandium, and gallium, and handed them over to Nutrien for adaptation."
In the laboratory.
Xu Yun was introducing the relevant situation to Yu Yuanyong:
"The final reply given by Nutrien was gallium metal, which is also the transition metal catalyst with the highest overall energy efficiency. The actual operation results after receipt were fully in line with expectations."
"Of course, because of this, their equipment quotation is much higher than expected."
Opposite him, Yu Yuanyong nodded clearly.
Among the three metals: lanthanum, scandium, and gallium, scandium is the most expensive.
According to the current price, the price of one ton of 99.9% grade scandium is 32,000 yuan.
Next is lanthanum.
Ton price 27750.02.
Gallium is the cheapest.
One ton costs only 2,805 yuan, which is ten times that of the above two metals.
at the same time.
Gallium is also the best choice for catalysis.
However, contrary to the price and effect, the difficulty of mass production of the three metals in industrial production lines is gradually increasing.
The same goes for equipment requirements.
Think of this.
Yu Yuanyong picked up a report from the table next to him, turned to a certain page, and introduced to everyone:
"Dr. Xu, to tell you the truth, we are currently stuck on the molecular sieve of the catalyst."
"Our team tried many methods, but in the end they all unfortunately failed."
"Don't talk about gallium, we haven't even made a breakthrough on scandium."
"Because no matter what kind of metal it is, the coordinated framework heteroatoms must be highly isolated in the molecular sieve."
"For example, the neighbors in Ti-O-Si are mainly Si-O-Si. On the other hand, Ti mainly exists in four-coordinated form. We must complete the atomic defect site reaction inside the container, but this is thermodynamically unfavorable.
"
At this moment, Lin Zhenhua on the side suddenly interrupted him and asked:
"Xiao Yu, how did Nutrien accomplish this step? Can you learn from their ideas?"
Yu Yuanyong shook his head, pointed at the computer at the other end and said:
"Nutrien uses a patented chemical grafting. The entire process is connected by seams, and no point can be changed."
"Not to mention the difficulty of the process, patent protection is difficult to overcome - they can include FOERDA-T632 in the Wassenaar Agreement, but Dr. Xu and others cannot plagiarize the patent, otherwise it will be like handing a knife to others.
It’s in hand.”
Lin Zhenhua opened his mouth when he heard this, as if he wanted to say something.
But in the end he didn't say anything.
As Yu Yuanyong said.
Huadun Biotechnology is not a small private workshop. Every step of Xu Yun and others will be watched with a magnifying glass, and they will risk their lives to find your sore feet.
Once the production capacity of ‘One Mantis Destruction’ is increased.
At that time, someone will inevitably instigate Nutrien to file a patent review and ask to verify whether patent infringement is involved.
Rogue?
Of course it's a bummer.
The embargoed equipment on the other side is not allowed to be imitated. This is the ultimate double standard.
Is it legal?
The answer is also yes.
Even if Huadun Biotech has the support of the University of Science and Technology or even the Academy of Sciences, it will not help.
Once this happens, what awaits them will be extremely severe punishment and crazy attacks from public opinion.
So Nutrien and the people behind it are not afraid at all of Huadun Biotechnology to copy this chemical grafting process, and perhaps they are eager for you to do this.
Then Xu Yun thought for a while and came up with a new idea:
"Director Yu, what do you think about using ion beam implantation?"
Yu Yuanyong blinked:
"Ion beam implantation method?"
Classmates who were Ions in their previous lives should all know this.
The so-called ion beam injection method refers to a method in which metal ions generated by ionization are accelerated in an electric field to form a high-speed ion beam and hit a designated substrate.
Due to the high speed of the ion beam, it can be injected into the surface layer and crystal lattice of the substrate to achieve regular effects.
However, unlike the chemical grafting method, the ion beam implantation method is mostly used in the fields of physics and materials science.
It is especially used in semiconductor surface modification and doping treatments, but is rarely used in the preparation of catalysts.
Seeing that Yu Yuanyong was a little confused, Xu Yun patiently explained:
"If you think about it, the metal ions in the ion beam are all positively charged and will repel each other and separate."
"So the metal ions driven into the matrix will basically remain in a highly isolated state."
"Let's add a chemical intermediate to it, such as catechol or something. Then, wouldn't a Y-shaped molecular sieve come out?"
Yu Yuanyong's eyes widened the more he listened, and his mouth opened involuntarily with a stunned expression.
A few seconds passed.
He suddenly made a fist with his right hand and struck it hard on the palm of his left hand:
"Yes, we can definitely use the method of introducing isotopic metal ions to force out the cations in the antibonding orbitals. Wow, look at my brain, why can't I think of this layer?"
When Xu Yun heard this, he smiled and said nothing.
Ion beam implantation method.
This was the last paper he published before leaving the field of scientific research in his previous life, which involved the defect site reaction transition effect of vanadium metal and molecular sieves.
doi is...ahem, I can't say it, because if I say it, I will lose my online name.
all in all.
The last paper before quitting is like your first love, and you may never forget it in your life.
Therefore, after learning that Yu Yuanyong and the others were stuck on the molecular sieve, Xu Yun immediately thought of this idea.
With Xu Yun's suggestion, the next thing is very simple.
In addition to the final product, the detection method of transition metal catalysis can also be determined by using ultraviolet Raman spectroscopy technology.
Especially in terms of molecular sieves.
The accuracy of the Raman spectrum peaks is even higher.
Therefore, Yu Yuanyong soon prepared for the toilet cleaning session of Raman spectroscopy.
Half an hour later.
Yu Yuanyong's team has completed preparations and officially started testing.
Ten minutes after the test started.
Transition metal heteroatoms begin to enter the molecular sieve framework.
at the same time.
In the UV-visible absorption spectrum, the charge transfer transition absorption between pπ of the skeleton oxygen atoms and dπ of the skeleton transition metal atoms immediately appeared.
More than twenty minutes passed.
A report appeared on the equipment table in front of Yu Yuanyong.
"The absorption peak is in the ultraviolet region between 200 and 350nm, and the center of the charge transfer transition absorption band is at 220nm..."
Yu Yuanyong excerpted several pieces of information and started calculations with Xu Yun at the same time.
five minutes later.
Xu Yun and Yu Yuanyong raised their heads one after another.
Lin Zhenhua noticed from the side.
At this moment, the expressions of both of them were a little solemn, and they were not as happy as expected.
Then the two looked at each other and heard Xu Yunde say:
"Director Yu, by how many orders of magnitude did the Raman signal you calculated increase?"
Yu Yuanyong frowned and reported a number:
"Five levels, how about you?"
Xu Yun raised the calculation paper in his hand toward him:
"It's also five, the word five doesn't work..."
Yu Yuanyong's brows suddenly furrowed even deeper. He looked at the report again and said with a puzzled expression:
"It's strange. The center of the charge transfer transition absorption band is around 220nm. The nearest ultraviolet laser close to this absorption band is 244nm. The data must be correct."
"According to the resonance Raman principle, when the energy of the excitation light source is close to the electron absorption band, resonance will inevitably occur between the electronic state and the vibrational state."
"The intensity of the Raman signal of the vibration mode related to this resonance conforms to the transition formula, so the magnitude of the four-coordination should be 6 to 7..."
Xu Yun also picked up the report, shook it like a doctor looking at a CT scan, and looked at it carefully.
A few minutes passed.
Xu Yun's expression suddenly became condensed, he pointed at a certain column and said to Yu Yuanyong:
"Director Yu, look here, why is there such a strong Raman peak at position 530?"
After a while.
Yu Yuanyong and Xu Yun thought of something at the same time, and said in unison:
"Selective excitation?"
Selective excitation.
It refers to a situation where the feedback from a statement is lower than expected within a certain range.
It may be man-made, or it may occur spontaneously due to lack of energy during the reaction.
Just like the gas stove in our lives.
Sometimes you turn on low heat because the dish must be stewed over low heat.
If necessary, you can always increase the heat.
But sometimes a small fire is turned on because the pipe is really running out of air.
What Xu Yun and others encountered was the latter situation, or an enhanced version of the latter - the gas pipeline in your home was out of gas, and at the same time, the gas company also sent the gas that was supposed to be delivered to your home to your neighbor's home.
, causing external...
Looking at the two people who were frowning like the street writers who saw the subscription in the background, Lin Zhenhua on the side couldn't help but said:
"Xiao Yu, Xiao Xu, my major is in industry. I don't know much about the concept of selective excitation. Anyway, is there any way we can solve it?"
After hearing this, Xu Yun pondered for a moment and said:
"I'm afraid it's difficult. We used scandium, which is the least difficult, and the ion beam chose iron, which has non-selective oxidation properties."
"Therefore, selective excitation occurs, mostly because certain pulse characteristics appear during the interaction phase."
"For example, iron ions and chemical intermediates produce some band feedback, delaying the reaction that should have occurred in the third minute to the fifth minute. Of course, this is just a necessity. In short, this kind of problem is difficult to solve in a short time.
"
"Our only choice at the moment is to bite the bullet and use this method to produce. After all, although the wave band is different from the straight line, we can still produce some products."
"Just like this, our production costs and efficiency will be affected."
Lin Zhenhua frowned:
"I see......"
Then Xu Yun pondered for a moment and was about to say some kind words to comfort Lin Zhenhua.
As a result, the words did not come out.
Lao Su on the side suddenly pulled his sleeve gently.
Xu Yun then stopped his mouth and turned his head.
He noticed that Lao Su gave him a look that said, "Come to the side and talk."
Xu Yun thought for a moment, pretended to be casual and patted Lao Su on the shoulder, pointed to the water dispenser not far away and said:
"Xiao Su, come with me to pour a few glasses of water for everyone. After doing this experiment for so long, everyone who doesn't drink water will have to do it."
Lao Su immediately understood:
"Okay, senior."
After walking to the water dispenser.
Xu Yun glanced around, lowered his voice and asked Lao Su:
"What's wrong?"
Lao Su first put a disposable water cup into the water outlet, pressed the switch, and said to Xu Yun:
"Xiao Xu, I don't know much about the specific concept you are talking about, but the so-called chemical intermediate reminds me of something. I wonder if it will inspire you."
"So I'll just talk about it, and you can listen to it as you wish."
"It's best if I can help. If I'm wrong, just ignore it."
Xu Yun put a plastic cup filled with water aside and replied:
"Su Gongdan said it doesn't matter."
Lao Su nodded, pondered for a moment, and said:
"When you were assembling the telescope that day, you mentioned something that I have never forgotten."
"What you roughly meant at that time was that the telescope needed a paraboloid as an intermediary carrier to reflect the object image, but the industrial level of the Song Dynasty was limited and could not process a spherical mirror that met your requirements."
"So then you took a different approach and used rotating mercury to achieve the parabolic effect."
"When I think about it, since the so-called chemical intermediate is also intended to have a relay effect, maybe its principle has nothing to do with the mercury paraboloid, but the two may have some similarities in nature."
"In this case, I would like to ask a question."
"Can we bypass the current situation and try to use liquid as this intermediate to avoid selective excitation through the special properties of liquid?"
heard these words.
Xu Yun was stunned for a moment, and then his pupils suddenly shrank!
What Lao Su said can be regarded as a classic operation he compared in the Northern Song Dynasty copy:
The copy at that time lacked a knife-edge instrument and an interferometer, so Xu Yun was unable to grind an accurate spherical lens.
Therefore, he cleverly used rotating mercury to realize the paraboloid, and achieved the same effect through an RC-like structure.
Although this operation has nothing to do with catechol.
But as Lao Su said.
The two are actually somewhat similar in nature.
One reflected light and the other feedback band both act as a relay.
So if it can be expanded through this idea.
Replace the catechol with some other special liquid.
At the same time, the centrifugal force of the liquid feeds back the band in which solid matter exists to the equilibrium, which seems...
