StudyonCatalyst For Acetic Acid Hydrogenation To Acetaldehyde

Acetaldehyde is an important basic chemical raw material and significant in organic synthesis such as medicines, spices and pesticides. In recent years, the process of producing acetaldehyde by hydrogenation of acetic acid has been paid much attention,due to the low cost and large scale production for acetic acid from methanol carbonylation.By comparing different active component and carrier, Pt-Fe/MCM-41catalyst was chosen as the object catalyst. Impregnation method was used to prepare Pt-Fe/MCM-41with different Pt contents as catalysts. The catalysts were characterized by several different methods such as BET, XRD, H2-TPR,H2-TPD, NH3-TPD. The activity of the catalysts is evaluated in isothermal fixed bed reactor. The performance of the catalysts was studied, as well as the influence of reaction conditions on the acetic acid conversion and the selectivity of acetaldehyde, ethanol, ethyl acetate.BET showed that when Pt content increased, the pore volume of the catalysts has little change. The diffraction peak of the catalysts is similar to those of Fe conponent.H2-TPR showed that there is interaction between Pt and Fe, andit also proved both the reduction temperatures were lower than the monometallic catalyst.H2-TPDshowed that there is interaction between Pt and Fe. NH3-TPD showed that the acid content is reduced when Pt and Fe concurrence.It is proved that for Pt-Fe/MCM-41catalyst, with the enhancement of Pt content, the selectivity of acetaldehyde increased firstly and then decreased in the range of Pt content froml%to10%. For2Pt-15Fe/MCM-41catalyst, at the temperature300-340℃, the pressure0.1-2MPa, gas space velocity1600-8000h-1, and the ratio of hydrogen and acetic acid3-30, higher conversion of acetic acid but lower selectivityof acetaldehyde would be obtained when temperature raise. With the increase of pressure, both the conversion of acetic acid and the selectivity of acetaldehyde would decrease. The conversion of acetic acid would drop when the ratio increase, while the selectivityof acetaldehyde first increased and then decreased. When the content of H2increase, both the conversion of acetic acid and the selectivity of acetaldehyde would first increased and then decreased.