Temperature controlled nucleation and crystal growth of the layered double hydroxides to improve its catalytic activity in dry reforming of methane

Anup Tathod, Chemical Engineering, Technion- Israel Institute of Technology, Haifa, Israel
Oz Gazit, Chemical Engineering, Technion- Israel Institute Of Technology, Haifa, Israel




The conversion of methane to syngas via dry reforming has attracted the attention of scientific community to fulfill the continuously increasing energy demand of the world. Layered double hydroxides (LDH) are the well known catalytic materials being used in dry reforming of methane and in many other catalytic conversions. For dry reforming LDH have the capacity to resist carbon formation, which is one of the main limiting factors of this reaction. In this work we synthesized nanoscale LDH materials with the aim to use them in dry reforming of methane. We have developed an efficient and highly reproducible method for LDH nanoparticles (NPs) synthesis, avoiding the use of organic structure directing agent and forgoing a lengthy aging process. It is shown that the nucleation temperature significantly affect the nucleation rate and crystal growth. At optimized temperature maximum nucleation rate can be achieved which leads to the formation of higher number of crystal with smaller size. Smaller crystal size is favorable for catalytic activity as active sites are proved to be associated with edges of crystal. The method has been successfully implemented for the synthesis of the Mg-Al and Ni-Al LDH nanoparticles with controlled lateral size. It is shown that by varying the nucleation temperature between 60 and -55 °C in conjunction with the fast addition of metal precursor we can obtain narrowly distributed isolated Mg-Al LDH NPs in the range of 20-200 nm. Effect of aging treatment on crystal growth has been studied in detail. Along with agglomeration of the particles enhanced stacking of the LDH layers was observed during aging treatment. Materials were characterized by DLS, XRD, HR-TEM and Cryo-TEM.