2.2. Characterization methods
X-ray diffraction (XRD) patterns were recorded using a DB
ADVANCE powder diffractometer with Ni-filtered Cu-Karadiation
(40 kV, 40 mA). N2 adsorption–desorption isotherms were measured using an ASAP2020M + C system after the sample was degassed under vacuum at 300C for 5 h. Pore size distribution was
determined using the conventional Barrett–Joyner–Halenda (BJH)
model. Scanning electron microscope (SEM) was performed with
a Hitachi S-4800 field emission scanning electron microscope. High
resolution transmission electron microscopy (HRTEM) images
were recorded using a JEM 100CX microscope with an accelerating
voltage of 200 kV.
2.3. Methanol to gasoline reaction test
The MTG reaction was conducted in a fixed bed reactor operating at 1.0 MPa and in the temperature range from 340 to 420C.
The cylindrical fixed bed reactor was made of stainless steel with
an internal diameter of 7 mm and was packed with 1.4 g of a catalyst. A plunger pump was used to feed liquid methanol (analytical
grade) at 0.06 mL/min into an evaporator where it was mixed with
N2as the carrier gas, heated and evaporated at 150C. The preheated reactant gas then entered the reactor at WHSV = 2.0 h
1
.
The reactor exit stream was separated into gas, liquid hydrocarbons and reaction water fractions using an ice-cooled condenser.
The gas fraction was analysed on-line using a GC (Agilent7890A)
fitted with both TDX-01 and Propake-Q columns and both a thermal conductivity detector (TCD) and a flame ionization detector
(FID). The liquid hydrocarbons were analysed using a GC
(Agilent7890A) fitted with a capillary column (OV-101) and an
FID. An atomic carbon balance between the inlet (carbon in methanol) and the exit (the sum of carbon in all identified species,
including unreacted methanol) streams under a steady state run
was typically within 15%, with the difference being attributed to
coke formation and carbon deposition.