KOH负载量对不同煤样加氢气化效果影响的实验研究

在加压固定床反应器中研究了碱金属催化剂KOH的添加量对呼和浩特煤和内蒙平庄煤加氢气化反应性的影响,并通过渣样酸洗水洗、原子吸收、XRD考察了煤结构中对气化反应活性有影响的因素。实验结果表明,催化剂的添加使呼和浩特煤的反应总气相产品产率明显提高,催化剂的饱和添加量约为15%。内蒙平庄煤在催化剂负载量增至30%时,才有较为明显的催化效果,但当催化剂负载量增至50%时,内蒙平庄煤60 min内的总气相产品产率仍低于64%。从XRD结果可以看出,随着加氢气化反应的进行,催化剂逐渐与煤中灰分反应失活,同时内蒙平庄煤中未反应的碳结构逐渐转化为活性较差的石墨,导致其反应后期的气化速率较缓慢。气化残渣中水可溶K与水不可溶但酸可溶K的比值与催化反应活性密切相关,当催化剂负载量小于20%时,内蒙平庄煤的高灰分可使大部分催化剂失活,导致其气化速率缓慢。

Effect of KOH loading on different coals hydrogasification

The effects of KOH loading on the hydrogasification of Hohhot(HH) coal and Pingzhuang(PZ) coal from Inner Mongolia were studied in a pressurized fixed-bed reactor, and the analysis methods of slag washing, atomic absorption and XRD were adopted to investigate the intrinsic characteristics of coal structure that affect the hydrogasification reactivity. The experimental results show that the total gas productivity of HH coal hydrogasification can be enhanced obviously by increasing the catalyst loading, and the catalyst loading saturation level is about 15%. On the other hand, KOH shows an inconspicuous effect on PZ coal hydrogasification unless the catalyst loading is higher than 30%, and the total gas productivity does not exceed 64% within 60 min reaction time when the catalyst loading is 50%. The XRD results indicate that as the hydrogasification proceeds, the catalyst is deactivated by reacting with the ash in coal, and the unreacted carbon in PZ coal is gradually transformed into less active graphite, resulting in a lower gasification rate at later reaction time. The ratio of water-soluble potassium to water-insoluble but acid-soluble potassium in the hydrogasification residue is closely related to the catalytic activity. When the catalyst loading is less than 20%, the high content ash in PZ coal will deactivate most of the loaded KOH, leading to a slow hydrogasification rate.