One‐step catalytic conversion of ethanol to butadiene in the fixed bed. II BINARY‐ AND TERNARY‐OXIDE CATALYSTS

Abstract

The activity of a large number of binary-and ternary-oxide catalyst systems comprising dchydrating and dehydrogenating components has been tested for the conversion of ethanol to butadiene in the fixed bed.-Alumina-zinc oxide (60 : 40) was the best catalyst, and it gave a maximum of 55.8% process yield of ethanol to butadiene a t a temperature of 425" and ethanol feed rate of 1.875 ml./h./g. of catalyst.Other promising binary catalysts are alumina-magnesium oxide (80 : 20), alumina-ferric oxide or -chromium oxide (60 : 40) and zirconia-ferric oxide (40 : 60). These gave maximum process yields of 47.8, 37.7, 47.2 and 39.7% respectively under optimum conditions.Of 40 different ternary-oxide catalyst systems tried, only alumina-chromium oxide-ferric oxide (80 : 5 : 15) was appreciably active giving 35.7% process yield of butadiene under optimum conditions.In general, the ternary-are less active than the binary-oxide systems. IntroductionIn Part I1 of this series were discussed the activities of various single oxide catalysts employed in the one-step catalytic conversion of ethanol to butadiene. It was concluded that only the oxides possessing both dehydrogenation and dehydration effects were comparatively active. In the light of the above conclusion, a thorough study on the activities of different binary and ternary oxide catalyst systems, comprising highly dehydrogenating and dehydrating components, has been carried out, and the present paper summarises the results obtained thereby.The published literature on the one-step catalytic conversion of ethanol to butadiene with binary and ternary oxide catalysts is extremely meagre. The reaction has now been studied with a large number of binary and ternary oxide catalyst systems (65 binary and 40 ternary), under widely varying operating conditions such as temperature, ethanol feed-rate, ethanol concentration in the feed, catalyst composition, etc.

Recent Breakthroughs in the Conversion of Ethanol to Butadiene

“…As the activity of Cr/MCM-41 was not reported, it is difficult to the role of barium in this improvement or if Ba and Cr had any synergic contribution in that regard. It should be noted that chromium-containing amphoteric mixed oxides were reported as active for the ETB reaction, but not silica-supported Cr 2 O 3 , evidencing some contribution from MCM-41 and/or Ba [26,41]. A decrease in ethanol conversion is observed over a period of 24 h. Coke formation on the catalytic surface, evidenced by thermal gravimetric analysis, is the likely cause of this deactivation.…”

“…Mixed oxides with either acid, basic and/or redox properties are a significant category of those. Bhattacharyya et al have thoroughly investigated the potential of binary and ternary metal oxide systems and discovered that a mixture of amphoteric alumina with basic and redox zinc oxide (Al2O3-ZnO (60:40)), is the most active catalyst (see Table 1) [26]. Other good catalysts included the mixture of alumina with basic magnesia or alumina with chromium oxide possessing redox properties.…”

Ethanol/acetaldehyde conversion into butadiene over sol–gel ZrO2–SiO2catalysts doped with ZnO

“…As reported in former literatures, 8,9 MgO-SiO 2 and ZrO 2 -SiO 2 were regarded as the two most promising catalytic system in ethanol to BD process, each for one-step and two-step, respectively. Dozens of studies were performed on MgO-SiO 2 catalytic system.…”

Modelling the effects of reaction temperature and flow rate on the conversion of ethanol to 1,3-butadiene

“…Usually, reaction variables are investigated using the "change-one-factor-at-atime" method; that is, one variable is changed while the other experimental conditions are kept constant [2,10,12,13,26,27,[29][30][31]. Based on this method, it has been found that temperature exerts an important nonlinear effect on 1,3-BD yields, as observed with help of different catalysts [13,19,26,30,31]. Similar studies have shown that the weight hourly space velocity (WHSV) also modifies 1,3-BD yields and selectivities [2,13,19,26,27,30,31].…”