Synthesis of layered double hydroxides through continuous flow processes: A review

•Continuous flow processes allow scaling-up of LDH production with constant quality.•Morphology and size of particles are controlled.•Evolution of the reactor design from tank to microfluidic technology is evidenced.•Heat and mass transfers are improved, and residence times are reduced.•Nanosheets, LDH-based hybrids and nanocomposites are obtained.