the 100-year-old [Haber-Bosch process](https://en.wikipedia.org/wiki/Haber_process), is a key industrial process to create artificial fertilizers.
It might be improved using computational chemistry methods that are enhanced by quantum computing.
Quantum Computing could improve the catalytic process for creating ammonia from atmospheric nitrogen, a process that currently requires high temperatures, high pressures, and carefully selected catalysts.
This process is so heat- and pressure-intensive that it consumes upwards of 2% of the world’s natural energy sources
The process gives us:
- [[Ammonia]],
- Urea,
- Ammonium Nitrate
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### Breakdown of Ammonia Production (Haber-Bosch process) x Catalysts Use
### **1. Feedstock Preparation (Gas Purification)**
Before ammonia synthesis begins, pure nitrogen (N₂) and hydrogen (H₂) gases must be prepared. Typically:
- **Nitrogen (N₂)** is sourced by removing oxygen and other impurities from air, generally through cryogenic air separation.
- **Hydrogen (H₂)** usually comes from methane (natural gas) reforming or water electrolysis.
Catalysts are prominently used during hydrogen production via methane reforming:
- **Steam Methane Reforming (SMR):** *Catalyst used: Nickel-based catalysts (temperature: ~700–1000°C)*
$CH_4+H_2O →CO + 3H_2 $
- **Water-Gas Shift Reaction (WGS):** Further hydrogen purification occurs via WGS: _Catalyst used:_
- High-temperature shift: Iron oxide-based catalysts
- Low-temperature shift: Copper-zinc oxide-based catalysts
$CO+H_2O →CO_2 + H_2 $
### **2. Gas Purification and Removal of Impurities**
The gas mixture (N₂ and H₂) obtained still contains impurities such as CO₂, CO, and residual H₂O. These impurities must be eliminated because they can poison catalysts later on:
- CO₂ is typically removed using solutions like amine scrubbing.
- Remaining CO and water vapor are further cleaned by catalytic methanation: $CO+3H_2→CH_4+H_2O $
- _Catalyst used:_ Nickel-based catalysts are again employed here to effectively convert remaining CO into less problematic methane (CH₄).
### **3. Ammonia Synthesis (The Haber-Bosch Reaction)**
This is the heart of ammonia production, where purified N₂ and H₂ combine directly to form ammonia:
$N2+3H2↔2NH3$
Conditions required are typically around 400–500°C and high pressures (100–250 bar) to improve yields. At this stage, catalysts are absolutely critical for making the reaction economically viable by reducing activation energy, speeding up reaction rates, and increasing yield efficiency.
- **Catalyst used:** Iron-based catalysts promoted with small quantities of potassium, aluminum oxide, calcium oxide, or magnesium oxide. These additives enhance catalytic activity, stability, and performance.
### **4. Cooling and Ammonia Separation**
After synthesis, the gas mixture (containing ammonia and unreacted nitrogen and hydrogen) is cooled, allowing ammonia to condense and separate out as liquid, leaving unreacted gases behind.
- The separated ammonia is collected and stored, while the unreacted gases (N₂ and H₂) are recycled back into the reactor, improving efficiency.
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### **Summary of Catalyst Use:**
Each catalyst significantly enhances efficiency and economics, making large-scale ammonia production feasible and commercially viable.
| **Reaction Step** | **Catalyst Used** |
| ------------------------------- | ----------------------------------------------------- |
| Steam Methane Reforming (SMR) | Nickel-based catalysts |
| Water-Gas Shift Reaction (WGS) | Iron oxide (high-temp), Copper-zinc oxide (low-temp) |
| Methanation (CO removal) | Nickel-based catalysts |
| Ammonia Synthesis (Haber-Bosch) | Iron-based catalysts (promoted by K, Al₂O₃, CaO, MgO) |
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[[Catalyst Formulations and Performance]]