Hydroxypropionic acid, hydroxypropionic acid derivatives, or mixtures thereof are dehydrated using a catalyst and a method to produce bio-acrylic acid, acrylic acid derivatives, or mixtures thereof. A method to produce the dehydration catalyst is also provided.

The present invention relates to a process for preparing acrylic acid from formaldehyde and acetic acid, comprising reacting formaldehyde and acetic acid via an aldol condensation in a reaction unit comprising n reaction zones arranged in series, each comprising an aldol condensation catalyst, where n is at least 2, and wherein at least one stream leaving a reaction zone, before being fed into the reaction zone immediately downstream, is mixed with a stream comprising formaldehyde and optionally comprising acetic acid. The present invention further relates to an apparatus for preparing acrylic acid from formaldehyde and acetic acid and to the use of this apparatus.

The present invention relates to a process for preparing acrylic acid from formaldehyde and acetic acid, comprising reacting formaldehyde and acetic acid via an aldol condensation in a reaction unit comprising n reaction zones arranged in series, each comprising an aldol condensation catalyst, where n is at least 2, and wherein at least one stream leaving a reaction zone, before being fed into the reaction zone immediately downstream, is mixed with a stream comprising formaldehyde and optionally comprising acetic acid. The present invention further relates to an apparatus for preparing acrylic acid from formaldehyde and acetic acid and to the use of this apparatus.

An electrode assembly includes a first electrode and a dielectric layer on the first electrode. The dielectric layer includes a bismuth compound of the formula Bi.sub.2(CrO.sub.4).sub.2Cr.sub.2O.sub.7, Pb.sub.4(BiO.sub.4)(PO.sub.4), Ag.sub.3BiO.sub.3, Bi.sub.2CdO.sub.2(GeO.sub.4), Bi.sub.2Te.sub.4O.sub.11, Cs.sub.6Bi.sub.4O.sub.9, Na.sub.3Bi(PO.sub.4).sub.2, Bi.sub.2(SeO.sub.3).sub.3, or a combination thereof. The electrode assembly can be particularly useful in various electronic devices.

An electrode assembly includes a first electrode and a dielectric layer on the first electrode. The dielectric layer includes a bismuth compound of the formula Bi.sub.2(CrO.sub.4).sub.2Cr.sub.2O.sub.7, Pb.sub.4(BiO.sub.4)(PO.sub.4), Ag.sub.3BiO.sub.3, Bi.sub.2CdO.sub.2(GeO.sub.4), Bi.sub.2Te.sub.4O.sub.11, Cs.sub.6Bi.sub.4O.sub.9, Na.sub.3Bi(PO.sub.4).sub.2, Bi.sub.2(SeO.sub.3).sub.3, or a combination thereof. The electrode assembly can be particularly useful in various electronic devices.