Preparation Of Cu-based Zeolite ERI Monolithic Catalyst And Its NH₃-SCR Performance

Copper-based catalysts have become the current hotspot because of their excellent NH₃-SCR activity and good hydrothermal stability.However,the use of copper-based catalysts still generally suffers from narrow activity windows,weak low-temperature activity and awful anti-poisoning ability,and their particles or powders exhibit low surface volume ratio and high bed pressure drop,which limits the industrial application.Currently,small pore zeolites with the cage type have abundant acid sites and isolated copper ions,which can improve the low-temperature activity of NH₃-SCR.Among them,ERI-type（erionite）zeolites consisted of eri and can-d6r cages（producing isolated copper ions）have been favored by researchers.Therefore,taking monolithic catalysts as the starting point,the development of copper-based ERI zeolite monolithic catalysts with high and low temperature activity and stability is the key point to promote their practical application of low-temperature NH₃-SCR denitrification as catalytic materials.This thesis focuses on the design,preparation of Cu-SAPO-17/cordierite and Cu-ERI/cordierite monolithic catalysts with ERI type for NH₃-SCR denitrification.The main contents are given as follows:（1）Cu-SAPO-17/cordierite monolithic catalyst was successfully prepared via a simple one-pot hydrothermal synthesis method.Seed crystals on the cordierite support not only improves the crystallinity of the catalytic membrane,but also are utilized as a Si source to participate in the growth of Cu-SAPO-17 crystals.The effects of synthesis conditions such as crystallization time,concentration of impregnation solution,and molar ratio of Cu-TEPA on the structure and performance of Cu-SAPO-17/cordierite catalyst were discussed in detail.As a comparison,a Cu-SAPO-17 zeolite powder was fabricated via the same as that of membrane.Cu-SAPO-17/Cor-120 synthesized under the optimal condition achieved a high NO degradation performance of over 90%from200 to 500℃,coupled with an excellent SO₂ resistance,especially H₂O resistance.These superior catalytic performances were much better than those of the Cu-SAPO-17 catalytic powder,which can be attributed to the existence of plenty of Cu²⁺species,Lewis acid sites and remarkable redox capacity.In addition,this monolithic catalyst still exhibits good denitration performance after six cycles of use.（2）A low-silica ERI/cordierite zeolite membrane was obtained by hydrothermal synthesis in an ultra-dilute solution system without organic templates.The Cu-ERI/Cor monolithic catalyst had the best activity by introducing a concentration of 1.0 M copper ions.At the same time,it was found that the H₂O/Si O₂ molar ratio of the synthetic sol had a significant impact on the NH₃-SCR performance of this catalyst.Compared to the previous chapter,the NO conversion of Cu-ERI/Cor-120 at 150℃could reach 100%;Through characterization and analysis,the excellent denitration performances of Cu-ERI/Cor catalysts resulted from the active species Cu²⁺and the zeolite membrane structure（specific surface area and morphology）;In addition,the Cu-ERI/Cor-120monolithic catalyst has excellent water resistance,sulfur resistance,and cyclic reusability;And the denitrification reaction mechanism of the monolithic catalyst was investigated by the use of situ infrared technology.