This paper investigates the impact of the oxidizing agent used in the physical activation of pyrolysis chars on activated carbons (AC), and their efficiency in tar cracking. The materials are produced from buckwheat husk, which is a French local biomass. Slow pyrolysis was chosen to favor the production of raw chars. Activated chars were then prepared by physical activation under steam or CO₂. The materials produced were physically and chemically characterized before being implemented in a fixed bed. The efficiency of materials in removing tar from syngas was studied, and ethylbenzene (EB) was chosen as the tar surrogate. The purification efficiency of the chars and AC was deduced from the EB conversion profiles in comparison with thermal cracking. The nature of the oxidizing agent impacted the porosity and mineral composition of the AC produced: CO₂ activation produced ACs with more carbon and less ash content. This is because the reduction of carbon with carbon dioxide presents a kinetic between 2 and 5 times slower than that conducted in the presence of steam. CO₂ activation also resulted in a higher relative microporosity (89%) than steam activation (61%), which itself gives a higher surface area. Pyrolysis char did not generate any interest for EB catalytic cracking, whereas ACs demonstrated higher performances. This is due to their higher level of porosity and higher ash content. BH–H₂O, which presents higher porosity, produced a better catalytic effect and was more resistant to deactivation.

本文研究了热解焦炭物理活化中使用的氧化剂对活性炭（AC）的影响及其在焦油裂解中的效率。这些材料是由荞麦皮制成的，荞麦皮是法国当地的生物质。选择慢速热解有利于生焦炭的生产。然后通过在蒸汽或CO ₂下进行物理活化来制备活化的炭。。在固定床中进行生产之前，先对所生产的材料进行物理和化学表征。研究了原料从合成气中去除焦油的效率，并选择乙苯（EB）作为焦油的替代物。与热裂化相比，由EB转化率曲线得出了焦炭和AC的净化效率。氧化剂的性质影响所产生的AC的孔隙率和矿物组成：CO ₂活化产生的AC具有更多的碳和更少的灰分。这是因为用二氧化碳还原碳的动力学要比在蒸汽存在下进行的动力学慢2至5倍。一氧化碳₂活化也产生了比蒸汽活化（61％）更高的相对微孔率（89％），而蒸汽活化本身给出了更大的表面积。热解炭对EB催化裂化没有产生任何兴趣，而ACs表现出更高的性能。这是由于它们较高的孔隙率和较高的灰分含量。BH–H ₂ O具有较高的孔隙率，产生了更好的催化效果，并且对失活具有更高的抵抗力。