Catalyst steam gasification of charcoal for syngas

doi:10.16085/j.issn.1000-6613.2018-1170

Abstract

Abstract:

Charcoal catalytic steam gasification for syngas was investigated using a lab-scale fixed bed gasifier to study the effects of different catalysts, temperature, and steam flow rate. Four alkali salts of KOH, K₂CO₃, KHCO₃ and KNO₃ were selected to pretreat charcoal. This paper discusses production of syngas from steam catalytic gasification of charcoal in a lab-scale ?xed bed reactor, using KOH, K₂CO₃, KHCO₃ and KNO₃ as catalysts. The effects of different catalysts, steam flow rate and gasification temperatures on carbon conversion rate, hydrogen production rate, volume fraction of gas composition and H₂/CO value of charcoal vaporization were investigated. The method of char absorbing catalyst was used to load catalyst in this work. The experiment used the absorption of potassium salt solution by carbon to load catalysts. The experimental results show that the four kinds of potassium salts can all improve the gasification efficiency of charcoal. With the same mass fraction of potassium salt solution, the catalytic activity of the four catalysts is in the order: KOH > K₂CO₃ > KHCO₃ > KNO₃. In addition, the rate of carbon conversion and hydrogen yield production increased with increasing concentration of the catalyst concentration, but the increasing trend slows down gradually. With further increase the trend of high concentration increased gradually, so the mass fraction of catalyst solution was more appropriate in the 4%—6% range. The H₂ composition and the H₂/CO ratio enhances with the increases of steam flow rate. The rise of temperature can promote carbon gasification reaction and the carbon conversion and hydrogen yield can reach 98.7% and 145.23g/kg at 950℃. The syngas of H₂/CO ratio in the range of 1.53—4.09 was obtained. A promising application for biomass is liquid fuel synthesis, such as methanol or dimethyl ether (DME).

Key words: charcoal, catalytic-gasification, syngas, H₂/CO ratio

摘要：

以木炭为原料，选用KOH、K₂CO₃、KHCO₃、KNO₃为催化剂，在上吸式固定床气化炉中，进行水蒸气催化气化制取合成气实验。考察了不同催化剂、催化剂用量、水蒸气流量、气化温度对木炭水蒸气气化的炭转化率、产氢率、气体组成体积分数和H₂/CO值的影响。实验通过炭吸收催化剂溶液来负载催化剂，实验结果表明：4种催化剂都可提高木炭气化效率，在浸渍相同质量分数的催化剂溶液下，催化活性顺序为KOH>K₂CO₃>KHCO₃>KNO₃。碳转化率及产氢率都随着催化剂溶液浓度的增加而增大，但浓度过高增加趋势逐渐变缓，催化剂溶液质量分数在4%~6%较为合适。增加水蒸气流量，气体产物中H₂体积分数增大，H₂/CO值增大。升高温度可促进炭气化反应，950℃时碳转化率和产氢率分别达到98.7%和145.23g/kg。实验可得到H₂/CO比1.53~4.09范围间的合成气，可用于合成甲醇、甲烷、二甲醚等燃料。

关键词: 木炭, 催化气化, 合成气, H₂/CO比

CLC Number:

Siyun NING,Hao YING,Wei XU,Yunjuan SUN,Hang YIN,Shuang JIA,Guanghua LIU. Catalyst steam gasification of charcoal for syngas[J]. Chemical Industry and Engineering Progress, 2019, 38(03): 1308-1315.

宁思云,应浩,徐卫,孙云娟,尹航,贾爽,刘光华. 木炭水蒸气催化气化制取合成气[J]. 化工进展, 2019, 38(03): 1308-1315.

Figures/Tables 17

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各组分质量分数%			各元素质量分数/%
挥发分	灰分	固定碳	C	H	O	N
15.11	3.17	81.72	83.4	1.41	12.05	0.28

各组分质量分数%			各元素质量分数/%
挥发分	灰分	固定碳	C	H	O	N
15.11	3.17	81.72	83.4	1.41	12.05	0.28

催化剂种类	合成气各组分体积分数/%					H₂/CO
催化剂种类	H₂	CO₂	CO	CH₄	CO+H₂	H₂/CO
KOH	60.47	14.1	24.33	1.10	84.80	2.48
K₂CO₃	58.62	15.00	24.88	1.50	83.49	2.36
KHCO₃	60.52	16.2	21.1	2.14	81.70	2.86
KNO₃	61.54	17.72	18.64	2.09	80.19	3.30

催化剂种类	合成气各组分体积分数/%					H₂/CO
催化剂种类	H₂	CO₂	CO	CH₄	CO+H₂	H₂/CO
KOH	60.47	14.1	24.33	1.10	84.80	2.48
K₂CO₃	58.62	15.00	24.88	1.50	83.49	2.36
KHCO₃	60.52	16.2	21.1	2.14	81.70	2.86
KNO₃	61.54	17.72	18.64	2.09	80.19	3.30

KOH质量分数/%	合成气组分体积分数/%					H₂/CO
KOH质量分数/%	H₂	CO₂	CO	CH₄	CO+H₂	H₂/CO
0	61.52	21.8	15.0	1.63	76.55	4.09
2	61.02	14.70	22.81	1.47	83.83	2.68
4	60.47	14.10	24.33	1.10	84.8	2.48
6	58.67	11.46	29.04	0.83	87.71	2.02
8	59.16	9.67	30.14	1.03	89.30	1.96
10	59.80	8.67	30.69	0.84	90.49	1.95