Citric Acid-Treated Zeolite Y (CY)/Zeolite Beta Composites as Supports for Vacuum Gas Oil Hydrocracking Catalysts: High Yield Production of Highly-Aromatic Heavy Naphtha and Low-BMCI Value Tail Oil

Abstract

Citric acid-treated zeolite Y (CY) and zeolite beta were mechanically mixed to obtain composite zeolites (CY-Beta) with various zeolite beta contents. The composite zeolites were used as the acid components of hydrocracking catalyst supports. The physical and chemical properties of the supports and catalysts were analyzed by N2 adsorption-desorption, XRD, SEM, and NH3-TPD. The mechanical mixing of CY and zeolite beta does not destroy the textual properties of the original zeolites. However, the acidity of the composite zeolite does not fit the linearly calculated value of the two zeolites because some of the acid sites are covered or reacted with other acid sites during the mixing process. In addition, weak acid sites favor the high yield of tail oil with low BMCI value. Compared with the CY-based and beta-based catalysts, the conversion and light oil yield of the CY-Beta-based catalyst was increased. The conversion, light oil yield, and petrochemical yield of the Ni-W/20CY-Beta(20)/ASA catalyst are 78.15, 65.0, and 83.7%, respectively. The BMCI value of the tail oil is 4.7, and the aromatic potential content (APC) of heavy naphtha (boiling point 65–177°C) is 42%. The 1,500 h pilot plant test of Ni-W/20CY-Beta(20)/ASA at 350°C, 7.0 MPa, 2.0 h−1 LHSV, and 800 H2/oil (v/v) shows that the activity remains stable during the 1,500 h evaluation. The heavy naphtha (APC about 41.0) yield of 41.2 illustrates that the catalyst has the ability to aromatize and cyclize the light fractions. The yield of diesel is about 25% with a cetane index (CI) of 59.2; the frozen point is lower than −45°C, and the cold filter plugging point is −35°C, demonstrating the isomerization performance for middle distillations. The yield of tail oil is 14.9% with a BMCI of 4.4, showing the high hydrogenation performance of the catalyst to transform the un-cracked tail oil to saturated hydrocarbon in order to reduce the BMCI value.

Solid-Phase Synthesis of Polysaccharides from Unprotected Glucose Catalyzed by Hβ Zeolites

“…Generally speaking, the acid modification of Hβ zeolites can well clean the pores inside the zeolites, and is a common method for the pretreatment of Hβ zeolites. − Therefore, in this work, three types of Hβ zeolites were acid-modified before further use. To determine whether acid treatment would destroy the original structure of Hβ zeolites, the framework structure and crystallinity of Hβ zeolites before and after acid modification were characterized by XRD.…”

Catalytic advances in vacuum gas oil hydrocracking

“…Diverse contents of β were used by Wei et al [20] in catalyst carrier when mixing two types of zeolites (β and citric acid treated Y) without terminating the original textural properties of each one. Since several acid sites were reacted or covered by other sites throughout amalgamation procedure, the acidity deviated from linearly estimated theoretical data.…”