Patent TW-202116411-A (TW)
Title: Uneven filling technology of catalyst and co sorbent in a sorption enhanced fixed-bed reactor to improve the efficiency of ethanol steam reforming
Inventor: SHEU WEN-JENN
IPC: B01J8/02
Filed: 2019-10-17
Abstract: The ethanol steam reforming with Ni/Al 2 O 3  as reforming catalyst is composed of the following three main reactions: 
 
     ethanol decomposition: C 2 H 5 OH→CH 4 +CO+H 2   
     water gas shift: CO+H 2 O CO 2 +H 2   
     methane steam reforming: CH 4 +H 2 O CO+3H 2   
     Under the condition of ethanol steam reforming, the addition of CO 2  sorbent (CaO) in the catalyst to absorb CO 2  (CaO+CO 2 →CaCO 3 ) will result in decreasing CH 4  and CO concentrations and increasing H 2  concentration in the product gas according to Le Chatelier’s principle. For a fixed-bed reactor, the common ways at present to allocate catalyst and sorbent are: 
 
     (3) The catalyst and sorbent are evenly mixed and distributed in the reactor 
 
     Advantages: easy configuration and really improving the efficiency of ethanol steam reforming. Disadvantages: incomplete use of sorbent and resulting in a great waste. 
 
     (4) The front segment is the pure catalyst and the latter is the pure sorbent 
 
     Advantages: simple configuration and more complete use of sorbent. Disadvantages: no real help for ethanol steam reforming in the latter segment and only after-treatment of the product generated in the front segment. 
 
     The capacity of CO 2  sorbent is significantly reduced when the sorbent is used to a certain extent. Therefore, this patent design is mainly combined with the above two configuration. Based on the same mass conditions of the sorbent and catalyst respectively, the H 2  yield and the operating time of sorbent can be improved by increasing the usage of CO 2  sorbent with uneven filling design of catalyst and CO 2  sorbent.  
 
     The main focus of this patent design is that not only the sorbent and the catalyst together can really improve the efficiency of ethanol steam reforming but also to take into account the use of CO 2  sorbent more complete. The novel way is to adopt catalyst/sorbent mixed in different ratio. From a physical point of view, the more sorbent is expected in the second segment if two segments are considered. For a comparison, both the catalyst mass and sorbent mass in uneven filling are the same as in even filling, respectively. According to the condition of same mass, only the mass ratio of catalyst/sorbent is varied in the front and latter segments, as shown in Figure 3. 
 
     According to Figure 3, the ethanol steam reforming starts to react at the inlet in the front segment where CO 2  has not yet been produced well such that the function of CO 2  sorbent there is partially useless due to a small amount of CO 2  generation. A smaller mass ratio of sorbent/catalyst is adopted in the front segment. Compared with the time flowing the whole reactor, the reaction time of CO 2  sorbent is smaller in the latter segment. Therefore, the greater mass ratio of sorbent/catalyst is adopted in the latter segment to enhance the reaction rate of CO 2  sorbent. Under the same mass conditions of both the sorbent and catalyst, an increase in the yield of H 2  is achieved because the usage time of CO 2  sorbent is extended.