生產純氫氣之催化薄膜反應器中氫氣滲透及產率之研究

STUDY ON HYDROGEN PERMEATION AND YIELD IN A CATALYTIC MEMBRANE REACTOR FOR PRODUCTION OF PURE HYDROGEN

趙志偉(Chih-Wei Chao)

指導教授 ： 洪賑城

大同大學/工程學院/化學工程學系所/碩士(2005年)

摘要

本研究之目標為建立一個含兩根鈀膜管之催化薄膜反應器，使用商業化MDC-3觸媒，以甲醇蒸氣重組生產純氫氣，並研究在反應器中的氫氣滲透量及回收率。
結果顯示，每次裝入新觸媒並在反應器中進行活化，氫氣滲透量即會減少，因為金屬觸媒(銅、鋅、鉻)可能沉積在鈀膜表面上。在進行288小時反應後，通入水蒸氣處理，氫氣滲透量增加了30％，因為水蒸氣可將鈀膜上的焦炭清除掉。氫氣滲透量數據藉由非線性迴歸套入壓力n次方之數學模式(n=0.69~0.92)，結果發現實驗數據與數學模式非常吻合。
甲醇蒸氣重組在催化薄膜反應器的實驗結果顯示，隨著WHSV減少，甲醇蒸氣重組的轉化率及氫氣回收率隨之增加，在所研究之WHSV範圍中，逆向水氣轉移反應有一最大值。在四個溫度-壓力之研究條件中，溫度為618K及壓力為11.8bar時，有最佳的氫氣回收率，此時WHSV為1.05 h-1，L/S為35.7 mol/h/m2，氫氣回收率為0.74，足夠讓甲醇蒸氣重組在催化薄膜反應器中達到熱量自我平衡。
在653K進行四小時活化後，MDC-3的觸媒活性在76小時之甲醇蒸汽重組實驗中呈穩定狀況。建議觸媒活化宜在催化薄膜反應器外進行，以防止鈀膜被金屬觸媒沉積，造成氫氣滲透量減少

關鍵字

甲醇蒸氣重組

並列摘要

The objective of this research is to set up a catalytic membrane reactor (CMR) with double Pd tubes for production of pure hydrogen by methanol steam reforming (MSR) using commercially available MDC-3 catalyst, and to study the hydrogen permeation and yield in the reactor.
The results show that hydrogen permeation decreases each time a new batch of catalyst is loaded into and regenerated in the reactor, due that the metal catalysts (Cu, Zn, Cr) might deposit onto the surface of Pd membrane. Treatment with steam, after 288 h of reaction, increases ~30% of the hydrogen permeation, due to removal of the coke on the Pd membrane. The hydrogen permeation data have been fitted to an n-th power model (n=0.69~0.92) of pressure by non-linear regression. The experimental data agree well with the model.
Results from MSR in CMR show that conversion for MSR and hydrogen yield increase with decreasing WHSV, while conversion for reverse water gas shift reaction has a maximum for the range of WHSV studied. Among four temperature-pressure conditions studied in this research, the condition with temperature of 618 K and pressure of 11.8 bar gives the best result in terms of hydrogen yield, where WHSV of 1.05 h-1, corresponding to L/S of 35.7 mol/h/m2, is enough for hydrogen yield of 0.74, the thermally self-balanced point for MSR in CMR.
The activity of MDC-3 catalyst, after hydrogen regeneration at 653 K for 4 h, has been found stable during the MSR experiment of 76 hours. It is suggested to regenerate the catalyst outside the membrane reactor to prevent Pd membrane from deposition of metal catalyst which may cause decreasing of hydrogen permeation.

並列關鍵字

methanol stream reforming

參考文獻

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